1 Vector
1 Vector
Easy
1.   The vector projection of a vector          on y-axis is
                                                                     10. A hall has the dimensions                           A fly
     (a) 5                          (b) 4                                starting at one corner ends up at a diametrically opposite
     (c)3                            (d) Zero                            corner. What is the magnitude of its displacement
2. Position of a particle in a rectangular-co-ordinate system is (3,       (a) 17 m                   (b) 26 m
   2, 5). Then its position vector will be                                 (c) 36 m                   (d) 20 m
      (a)                          (b)
      (c)                          (d) None of these                  11. 100 coplanar forces each equal to 10 N act on a body. Each
                                                                          force makes angle       with the preceding force. What is the
3.   If a particle moves from point P (2,3,5) to point Q (3,4,5). Its     resultant of the forces
     displacement vector be                                                 (a) 1000 N                  (b) 500 N
       (a)                         (b)                                      (c)  250  N                 (d) Zero
      (c)                          (d)
                                                                      12. The magnitude of a given vector with end points (4, – 4, 0)
                                                                          and (– 2, – 2, 0) must be
4.   A force of 5 N acts on a particle along a direction making an
     angle of 60° with vertical. Its vertical component be                  (a) 6                         (b)
       (a) 10 N                       (b) 3 N                               (c) 4                         (d)
       (c) 4 N                        (d) 2.5 N
6.   Vector    makes equal angles with x,y and z axis. Value of its (a)                                  (b)
     components (in terms of magnitude of      ) will be                    (c)                           (d)
      (a)                          (b)
                                                                      15. The unit vector along     is
                                                                            (a)                           (b)
      (c)                          (d)
                                                                            (c)                           (d)
7.   If                    the direction of cosines of the vector
     are
                                                                      16. A vector is represented by                    . Its length in XY
      (a)                                (b)                              plane is
                                                                            (a) 2                         (b)
                                                                            (c)                           (d)
(c) (d)
                                                                   17. Five equal forces of 10 N each are applied at one point and all
8.   The vector that must be added to the vector                and
                                                                       are lying in one plane. If the angles between them are equal,
                     so that the resultant vector is a unit vector     the resultant force will be
     along the y-axis is                                                 (a) Zero                      (b) 10 N
       (a)                         (b)                                   (c) 20 N                      (d)
      (c)                          (d) Null vector
                                                                      18. The angle made by the vector                with x- axis is
9.   How many minimum number of coplanar vectors having                     (a) 90°                       (b) 45°
     different magnitudes can be added to give zero resultant               (c) 22.5°                     (d) 30°
       (a) 2                        (b) 3
       (c) 4                        (d) 5
Vector
Easy
19. Any vector in an arbitrary direction can always be replaced by
    two (or three)                                                       (c)                          (d)
      (a) Parallel vectors which have the original vector as their
          resultant
                                                                   28. Surface area is
      (b) Mutually perpendicular vectors which have the original
          vector as their resultant                                      (a) Scalar                       (b)Vector
      (c) Arbitrary vectors which have the original vector as            (c) Neither scalar nor vector    (d)Both scalar and vector
          their resultant
      (d) It is not possible to resolve a vector                   29. With respect to a rectangular cartesian coordinate system,
                                                                       three vectors are expressed as
20. Angular momentum is
                                                                                   ,                and           where           are
      (a) A scalar                   (b) A polar vector
                                                                       unit vectors, along the X, Y and Z-axis respectively. The unit
      (c) An axial vector            (d) None of these
                                                                       vectors along the direction of sum of these vector is
        (a)                              (b)
                                                                     45. If the resultant of the two forces has a magnitude smaller than
        (c)                              (d)                             the magnitude of larger force, the two forces must be
                                                                            (a) Different both in magnitude and direction
37. A truck travelling due north at 20 m/s turns west and travels at        (b) Mutually perpendicular to one another
    the same speed. The change in its velocity be                           (c) Possess extremely small magnitude
      (a) 40 m/sN–W                 (b)          m/s N–W                    (d) Point in opposite directions
        (c) 40 m/s S–W                   (d)    m/sS–W
                                                                    46. Forces       and      act on a point mass in two mutually
38. If the sum of two unit vectors is a unit vector, then magnitude     perpendicular directions. The resultant force on the point
    of difference is                                                    mass will be
        (a)                              (b)                                (a)                           (b)
      (d)
                                                                     62. What is the angle between      and the resultant of
      (a)                          (b)
                                                                     68. A body is at rest under the action of three forces, two of
      (c)                          (d)                                   which are                       the third force is
                                                                            (a)                          (b)
Vector
Easy
        (c)                        (d)
                                                                    77. Which pair of the following forces will never give
69. A plane is revolving around the earth with a speed of 100           resultant force of 2 N
    km/hr at a constant height from the surface of earth. The             (a) 2 N and 2 N              (b) 1 N and 1 N
    change in the velocity as it travels half circle is
(a)200 km/hr                         (b) 150 km/hr
                                                                          (c) 1 N and 3 N              (d) 1 N and 4 N
        (c)                        (d) 0
                                                                 78. Two forces 3N and 2 N are at an angle  such that the
70. What displacement must be added to the displacement              resultant is R. The first force is now increased to 6N and the
                                                                     resultant become 2R. The value of  is
                     to give a displacement of 7.0 m pointing in
    the x- direction                                                   (a) 30°                       (b) 60°
        (a)                        (b)                                    (c) 90°                      (d) 120°
        (c)                        (d)
                                                               79. Three concurrent forces of the same magnitude are in
                                                                   equilibrium. What is the angle between the forces ? Also
71. A body moves due East with velocity 20 km/hour and then        name the triangle formed by the forces as sides
    due North with velocity 15 km/hour. The resultant velocity       (a) 60° equilateral triangle      (b)120° equilateral triangle
(a)       5 km/hour               (b) 15 km/hour                     (c) 120°, 30°, 30° an isosceles triangle(d) 120° an obtuse
      (c) 20 km/hour              (d) 25 km/hour                     angled triangle
72. The magnitudes of vectors           and are 3, 4 and 5 units 80. If                             , then angle between       and
      respectively. If         , the angle between and is            will be
                                                                        (a) 90°                         (b) 120°
       (a)                          (b)                                 (c) 0°                         (d) 60°
       (c)                        (d)                              81. The maximum and minimum magnitude of the resultant
                                                                       of two given vectors are 17 units and 7 unit
                                                                       respectively. If these two vectors are at right angles to
73. While travelling from one station to another, a car travels 75     each other, the magnitude of their resultant is
    km North, 60 km North-east and 20 km East. The minimum               (a) 14                    (b) 16
    distance between the two stations is
                                                                         (c) 18                    (d) 13
       (a) 72 km                  (b) 112 km
       (c) 132 km                 (d) 155 km
                                                                   82. The vector sum of two forces is perpendicular to their vector
                                                                       differences. In that case, the forces
74. A scooter going due east at 10 ms–1 turns right through an           (a) Are equal to each other in magnitude
    angle of 90°. If the speed of the scooter remains unchanged in       (b) Are not equal to each other in magnitude
    taking turn, the change is the velocity of the scooter is
                                                                         (c) Cannot be predicted
(a)20.0 ms–1 south eastern direction(b)Zero
                                                                         (d) Are equal to each other
      (c) 10.0 ms–1 in southern direction(d)14.14 ms–1 in south-
      west direction
                                                                   83. y component of velocity is 20 and x component of velocity is
                                                                       10. The direction of motion of the body with the horizontal at
75. A person goes 10 km north and 20 km east. What will be             this instant is
    displacement from initial point
                                                                         (a)                            (b)
      (a) 22.36 km                  (b) 2 km
                                                                         (c) 45°                        (d) 0°
      (c) 5 km                      (d) 20 km
                                                                                               (a) / 2                                                                      (b
86. The vectors          and              are added. The magnitude of
                                                                                               / 3
    the sum of these vector is
                                                                                               (c)                                  (d) / 4
      (a)                               (b) 38
      (c) 238                           (d) 560
                                                                                      95. If                             and                            then value of
                                                                                                       will be
87. Two vectors                        are such that                         .
    Then                                                                                       (a)                                   (b)
      (a)                                (b)                                                   (c)                                   (d)
      (c)                               (d)
                                                                                      96. The torque of the force                                            acting at the
88. If a vector                     is perpendicular to the vector                        point                                m about the origin be
                       . Then the value of          is                                         (a)                                   (b)
                                                                                               (c)                                   (d)
        (a) –1                           (b)
        (c)                              (d) 1
                                                                                      97. If                   then which of the following statements is
                                                                                          wrong
89. If two vectors               and                               are parallel                (a)                                   (b)
    to each other then value of  be                                                           (c)                                   (d)
        (a) 0                            (b) 2
        (c) 3                            (d) 4                                        98. If a particle of mass m is moving with constant velocity v
                                                                                          parallel to x-axis in x-y plane as shown in fig. Its angular
                                                                                          momentum with respect to origin at any time t will be
90. A body, acted upon by a force of 50 N is displaced through a
    distance 10 meter in a direction making an angle of 60° with                               (a)                                   (b)
    the force. The work done by the force be                                                   (c)                                   (d)
        (a) 200 J                        (b) 100 J
        (c) 300                          (d) 250 J                                    99. Consider two vectors                              and                      The
                                                                                          magnitude of the scalar product of these vectors is
91. A       particle   moves    from     position                                to         (a) 20                       (b) 23
                                   due        to    a    uniform     force       of            (c)                                   (d) 26
                            If the displacement in meters then work
    done will be                                                                      100.Consider a vector                                 Another vector that is
      (a)     100 J                      (b) 200 J                                        perpendicular to          is
        (c) 300 J                        (d) 250 J                                             (a)                                   (b)
                                                                                               (c)                                   (d)
92. If for two vector     and    , sum                   is perpendicular to the
    difference             . The ratio of their magnitude is                          101.       Two vectors                and       are at right angles to each
        (a) 1                            (b) 2
                                                                                          other, when
        (c) 3                            (d) None of these
                                                                                            (a)                                      (b)
                                                                                               (c)                                   (d)
93. The angle between the vectors                  and     is    The value of
    the triple product                     is                                         102.If                                   and         is finite, then
        (c)                              (d)
Vector
Easy
         (c)           and            are     mutually      perpendicular(d)          (c) 160 J                       (d) 190 J
                                                                                112.A particle moves in the x-y plane under the action of a force
                                                                                    such that the value of its linear momentum             at anytimet is
103.A force                         Newton is applied over a particle
                                                                                                                   The angle        between       and    at
    which displaces it from its origin to the point
                                                                                    a given time t. will be
    metres. The work done on the particle is
     (a) – 7 J                      (b) +13 J                                         (a)                             (b)
     (c) +7 J                       (d) +11 J                                         (c)                             (d)
104.The        angle    between     two     vectors                       and 113.The area of the parallelogram represented by the vectors
                       is                                                                     and             is
         (a) 0°                             (b) 90°                                   (a) 14 units                    (b) 7.5 units
         (c) 180°                           (d) None of the above                     (c) 10 units                    (d) 5 units
105.The angle between the vectors                     and        is             114.A vector      is along the positive X-axis. If its vector product
          (a) 30°                           (b) 45°                                 with another vector       is zero then      could be
         (c) 60°                            (d) 90°
                                                                                       (a)                            (b)
107.If                      then angle between    and       is                  116.The angle between vectors                 and             is
         (a) 0°                             (b) 30°                                   (a) Zero                        (b) 
         (c) 45°                            (d) 60°                                   (c)                             (d)
108.A force                             acting on a body, produces a 117.What is the angle between                            and
    displacement                       Work done by the force is
          (a) 10 units                   (b) 18 units                     (a) 0                                       (b)
         (c) 11 units                       (d) 5 units
                                                                                      (c)                             (d)
109.The angle between the two vectors                                     and
                       will be
                                                                                118.The resultant of the two vectors having magnitude 2 and 3 is
         (a) Zero                           (b) 45°                                 1. What is their cross product
         (c) 90°                            (d) 180°                                   (a) 6                       (b) 3
                                                                                       (c) 1                       (d) 0
110.The vector                        and                                 are
    perpendicular to each other. The positive value of a is                     119.Let                                      be any vector. Another
       (a) 3                       (b) 4                                            vector     which is normal to A is
      (c) 9                        (d) 13
                                                                                      (a)                             (b)
         (c)                             (d)                                     130.What is the unit vector perpendicular to the following vectors
                                                                                                  and
                                                                                          (a)                           (b)
121.A vector          points vertically upward and           points towards
    north. The vector product               is
                                                                                          (c)                           (d)
         (a) Zero                        (b) Along west
         (c) Along east                  (d) Vertically downward
                                                                                 131.The area of the parallelogram whose sides are represented by
122.Angle between the vectors                  and            is                     the vectors        and           is
         (a) 90°                         (b) 0°                                           (a)       sq.unit             (b)        sq.unit
         (c) 180°                        (d) 60°                                          (c)       sq.unit             (d)        sq.unit
124.If force                      and displacement                       then 133.Two vector A and B have equal magnitudes. Then the vector
    the work done is                                                              A + B is perpendicular to
       (a)                               (b)                                              (a)                           (b) A – B
         (c)                             (d)                                              (c) 3A – 3B                   (d) All of these
125.If                            then angle between         and      will be    134.Find the torque of a force                              acting at the
          (a) 30°                        (b) 45°                                     point
         (c) 60°                         (d) 90°
                                                                                           (a)                                                               (b
126.In an clockwise system
         (a)                             (b)                                              (c)                           (d)
         (c)                             (d)
                                                                                    (b)
141.Dot product of two mutual perpendicular vector is
      (a) 0                      (b) 1                                              (c)
     (c)                        (d) None of these
                                                                                    (d)
142.When                          then
         (a)     and   are perpendicular to each other                        149.If a body is in equilibrium under a set of non-collinear forces,
         (b)     and   act in the same direction                                  then the minimum number of forces has to be
                                                                                      (a) Four                    (b) Three
         (c)     and   act in the opposite direction
                                                                                     (c) Two                      (d) Five
         (d)     and   can act in any direction
                                                                              150.How many minimum number of non-zero vectors in different
143.If                          then the value of             is                  planes can be added to give zero resultant
                                                                                    (a) 2                        (b) 3
         (a)                          (b)                                           (c) 4                        (d) 5
         (c)                          (d)                                     151.As shown in figure the tension in the horizontal cord is 30 N.
                                                                                  The weight W and tension in the string OA in Newton are
                                                                              152.Two cars are moving in the same direction with the same
145.A force                         is applied over a particle which              speed 30 km/hr. They are separated by a distance of 5 km, the
    displaces it from its original position to the point                          speed of a car moving in the opposite direction if it meets
    m. The work done on the particle is                                           these two cars at an interval of 4 minutes, will be
      (a) + 11 J                      (b) + 7 J                                     (a) 40 km/hr                    (b) 45 km/hr
Vector
Easy
      (c) 30 km/hr                  (d) 15 km/hr                    160.A man sitting in a bus travelling in a direction from west to
                                                                        east with a speed of 40 km/h observes that the rain-drops are
153.A man standing on a road hold his umbrella at 30° with the          falling vertically down. To the another man standing on
    vertical to keep the rain away. He throws the umbrella and          ground the rain will appear
    starts running at 10 km/hr. He finds that raindrops are hitting       (a) To fall vertically down
    his head vertically, the speed of raindrops with respect to the
                                                                          (b) To fall at an angle going from west to east
    road will be
       (a) 10 km/hr                 (b) 20 km/hr                          (c) To fall at an angle going from east to west
       (c) 30 km/hr                 (d) 40 km/hr                          (d) The information given is insufficient to decide the
                                                                               direction of rain.
154.A boat is moving with a velocity 3i + 4j with respect to ground.
    The water in the river is moving with a velocity – 3i – 4jwith 161.A boat takes two hours to travel 8 km and back in still water.
    respect to ground. The relative velocity of the boat with          If the velocity of water is 4 km/h, the time taken for going
    respect to water is                                                upstream 8 km and coming back is
      (a) 8j                        (b) – 6i – 8j
                                                                         (a) 2h
      (c) 6i +8j                    (d)
                                                                         (b) 2h 40 min
                                                                             (c) 1h 20 min
155.A 150 m long train is moving to north at a speed of 10 m/s. A
    parrot flying towards south with a speed of 5 m/s crosses the            (d) Cannot be estimated with the information given
    train. The time taken by the parrot the cross to train would be:
                                                                       162.A 120 m long train is moving towards west with a speed of 10
      (a) 30 s                      (b) 15 s                               m/s. A bird flying towards east with a speed of 5 m/s crosses
      (c) 8 s                       (d) 10 s                               the train. The time taken by the bird to cross the train will be
                                                                           (a) 16 sec                    (b) 12 sec
156.A river is flowing from east to west at a speed of 5 m/min. A
    man on south bank of river, capable of swimming 10m/min in             (c) 10 sec                    (d) 8 sec
    still water, wants to swim across the river in shortest time. He
    should swim                                      [BHU 1998]      163.A boat crosses a river with a velocity of 8 km/h. If the
       (a) Due north                                                     resulting velocity of boat is 10 km/h then the velocity of river
       (b) Due north-east                                                water is
       (c) Due north-east with double the speed of river                   (a) 4 km/h                    (b) 6 km/h
       (d) None of these
                                                                           (c) 8 km/h                    (d) 10 km/h
169.         Find the resultant of three vectors            and 175.A metal sphere is hung by a string fixed to a wall. The sphere
             shown in the following figure. Radius of the circle    is pushed away from the wall by a stick. The forces acting on
                                            C                                           the sphere are shown in the second diagram. Which of the
    is R.                                             B
                                                                                        following statements is wrong
       (a) 2R                               45o
                                               45o                                        (a)
                                                          A
       (b)                              O
                                                                                          (b)
       (c)                                                                                (c)
       (d)                                                                                (d)
170.    Figure shows ABCDEF as a regular hexagon. 176.The speed of a boat is 5 km/h in still water. It crosses a river
                                                      of width 1 km along the shortest possible path in 15 minutes.
    What is the value of         E       D
                                                                                        The velocity of the river water is
       (a)                                                                                 (a) 1 km/h                    (b) 3 km/h
       (b)                                      F                        C                (c) 4 km/h                     (d) 5 km/h
                                                               O
       (c)
                                                                177.A man crosses a 320 m wide river perpendicular to the current
       (d)                                            A              B
                                                                    in 4 minutes. If in still water he can swim with a speed 5/3
                                                                    times that of the current, then the speed of the current, in
171.The length of second's hand in watch is 1 cm. The change in     m/min is
    velocity of its tip in 15 seconds is                              (a) 30                        (b) 40
                                                                      (c) 50                        (d) 60.
      (a) Zero                       (b)
                                                                                 178.                         represents a unit vector when c is
       (c)                            (d)                                                 (a) – 0.2                     (b)
                                                                                          (c)                           (d) 0
      (a)                                 (b)
                                                                          188.     Figure below shows a body of mass M moving
      (c)                                 (d) None of these                   with the uniform speed on a circular path of radius, R.
                                                                              What is the
                                                                                       P2 change in acceleration in going from     to
182.A car travels 6 km towards north at an angle of 45° to the east                                        v
    and then travels distance of 4 km towards north at an angle of
    135° to the east. How far is the point from the starting point.                                            P1
                                                                                                  R
    What angle does the straight line joining its initial and final
    position makes with the east
       (a)            and                       (b)
                                                                                   (c)                                      (d)
183.Given that              = 0 out of three vectors two are equal in
    magnitude and the magnitude of third vector is     times that
    of either of the two having equal magnitude. Then the angles 189.      A particle is moving on a circular path of radius r
    between vectors are given by                                     with uniform velocity v. The change in velocity when
      (a) 30°, 60°, 90°            (b) 45°, 45°, 90°                                P
                                                                     the particle moves  from P to Q is
      (c) 45°, 60°, 90°            (d) 90°, 135°, 135°                           r
                                                                                         O       40o           v
                                                                                   (a)                                      (b)
Vector
Easy
      (c) Both (a) and (b)            (d) None of these
                                                                  200.A steam boat goes across a lake and comes back (a) On a
193.Two      constant    forces                        (N)   and      quite day when the water is still and (b) On a rough day when
                                                                      there is uniform air current so as to help the journey onward
                      (N) act on a body and displace it from the      and to impede the journey back. If the speed of the launch on
    position                        (m)      to    the   position     both days was same, in which case it will complete the
                                                                      journey in lesser time
                              (m). What is the work done
                                                                        (a) Case (a)                  (b) Case (b)
      (a) 9 J                       (b) 41 J
                                                                        (c) Same in both              (d) Nothing can be predicted
      (c) – 3 J                     (d) None of these
                                                                          202.A swimmer can swim in still water with speed  and the river
195.Which of the following is the unit vector perpendicular to                is flowing with velocity v/2. To cross the river in shortest
    and                                                                       distance, he should swim making angle  with the upstream.
                                                                              What is the ratio of the time taken to swim across the shortest
      (a)                             (b)                                     time to that is swimming across over shortest distance
                                                                                   (a) cos                    (b) sin 
      (c)                             (d)                                          (c) tan                    (d) cot 
(a) (b)
(c) (d) A = 5
199.Two trains along the same straight rails moving with constant
    speed 60 km/hr and 30 km/hr
       respectively towards each other. If at time              , the
      distance between them is 90 km,
      the time when they collide is
      (a) 1 hr                        (b) 2 hr
      (c) 3 hr                        (d) 4 hr
                                                                208.      The time period of a simple pendulum is
204.    The period of oscillation of a simple
                                                                   given by                 . The measured value of the
  pendulum is               . Measured value of           is
                                                                   length of pendulumis               known to a
         from meterscale having a minimum division                 accuracy. The time for             oscillations of the
  of          and time of one complete oscillation is              pendulum is found to be              secondusing a clock
         measured fromstopwatch of                                 of       resolution. The percentage accuracy in the
  resolution. The percentage error in the
                                                                   determination of            using this pendulum is       .The
  determination of '          will be
                                                                   value of           to the nearest integer is:-
        (a)                     (b)
                                                                          (a)                (b)             (c)             (d)
        (c)                     (d)
        (a)                     (b)
        (c)                     (d)