1.
A car is moving with uniform velocity on a rough (c) 5 mg (d) mg
horizontal road. Therefore, according to Newton's first 7. A spring balance and a physical balance are kept in a
law of motion lift. In these balances equal masses are placed. If now
(a) No force is being applied by its engine the lift starts moving upwards with constant
(b) A force is surely being applied by its engine acceleration, then
(c) An acceleration is being produced in the car (a) The reading of spring balance will increase and
(d) The kinetic energy of the car is increasing the equilibrium position of the physical balance
2. A person is sitting in a travelling train and facing the will disturb
engine. He tosses up a coin and the coin falls behind (b) The reading of spring balance will remain
him. It can be concluded that the train is unchanged and physical balance will remain in
equilibrium
(a) Moving forward and gaining speed (c) The reading of spring balance will decrease and
(b) Moving forward and losing speed physical balance will remain in equilibrium
(c) Moving forward with uniform speed (d) The reading of spring balance will increase and
(d) Moving backward with uniform speed the physical balance will remain in equilibrium
3. A block can slide on a smooth inclined plane of 8. As shown in the figure, two equal masses each of 2 kg
are suspended from a spring balance. The reading of
inclination kept on the floor of a lift. When the lift
the spring balance will be
is descending with a retardation a, the acceleration of
the block relative to the incline is
(a) Zero
(a) (b)
(b) 2 kg
(c) (d)
(c) 4 kg
4. A 60 kg man stands on a spring scale in the lift. At
(d) Between zero and 2 kg
some instant he finds, scale reading has changed from
60 kg to 50kg for a while and then comes back to the 9. A player kicks a football of mass 0.5 kg and the
original mark. What should we conclude ? football begins to move with a velocity of 10 m/s. If
the contact between the leg and the football lasts for
(a) The lift was in constant motion upwards
(b) The lift was in constant motion downwards
sec, then the force acted on the football should be
(c) The lift while in constant motion upwards, is
(a) 2500 N (b) 1250 N
stopped suddenly
(c) 250 N (d) 625 N
(d) The lift while in constant motion downwards, is
suddenly stopped 10. The engine of a jet aircraft applies a thrust force of
5. When a body is acted by a constant force, then which during take off and causes the plane to attain a
of the following quantities remains constant velocity of 1 km/sec in 10 sec. The mass of the plane
is
(a) Velocity (b) Acceleration
(c) Momentum (d) None of these (a) (b)
6. A man of weight mg is moving up in a rocket with
(c) (d)
acceleration 4 g. The apparent weight of the man in
11. A force of 50 dynes is acted on a body of mass 5 g
the rocket is
which is at rest for an interval of 3 seconds, then
(a) Zero (b) 4 mg impulse is
14. Two masses M and m are connected by a weightless
(a) (b)
string. They are pulled by a force F on a frictionless
(c) (d) horizontal surface. The tension in the string will be
12. Two weights and are suspended from the ends
of a light string passing over a smooth fixed pulley. If
the pulley is pulled up at an acceleration g, the tension
in the string will be
(a) (b)
(a) (c) (d)
15. In the above question, the acceleration of mass m is
(b)
(a) (b)
(c) (c) (d)
16. Three weight A, B and C are connected by string as
shown in the figure. The system moves over a
(d) frictionless pulley. The tension in the string
13. The masses of 10 kg and 20 kg respectively are connecting A and B is (where g is acceleration due to
gravity)
connected by a massless spring as shown in figure. A
(a) g
force of 200 N acts on the 20 kg mass. At the instant
shown, the 10 kg m ass has acceleration . (b)
What is the acceleration of 20 kg mass
(c)
(d)
(a) (b)
(c) (d) Zero
