Seat No.

: _____

Republic of the Philippines

OPENSOURCE REVIEW GROUP for REE and RME
https://www.facebook.com/groups/ree.opensource
ELECTRICAL ENGINEERING DIVISION

WEEKLY ASSESSMENT QUIZ No.: 4 WEEK 4: ESAS PART 1

JUNE 17, 2023 08:00 a.m. – 10:30 a.m
---------------------------------------------------------------------------------------------------------------------

T
INSTRUCTION: Select the correct answer for each of the following questions. Mark
only one answer for each item by shading the box corresponding to the letter of your

N
choice on the answer sheet provided. STRICTLY NO ERASURES ALLOWED.

MULTIPLE CHOICE

OI
1. A 3 cm wavelength radar is located at the origin of x-y coordinate system. A car
located at x = 100 m and y = 200 m is heading east (x-direction) at a speed of
120 kph. What is the Doppler frequency measured by the radar?
SP
A. 955.33 Hz C. -955.33 Hz
B. -993.71 Hz D. 993.71 Hz

2. A flywheel whose moment of inertia is 4 kg-m^2 is acted by a torque of 50 N-m.

Six seconds after starting from an angular velocity of 40 rad/s the flywheel will
have turned through,
ES
A. 225 rad C. 465 rad
B. 315 rad D. 3053 rad

3. A 7 kg bowling ball hangs from the end of a 2.5 m rope. The ball is pulled back
until the rope makes a 45° angle with the vertical. What is the gravitational
C

potential energy of the system?

A. 48 J C. 43 J
B. 50 J D. 55 J
AC

4. A ball is thrown upward with an initial velocity of 15 m/s at an angle of 30° with
the horizontal. The thrower stands near the top of a long hill which slopes
downward at an angle of 20°. When does the ball strike the slope?
A. 3.89 s C. 2.28 s
B. 2.49 s D. 3.66 s

PAGE 1
 5. A stone weighing 45 N is tied to one end of a cord 90 cm long. The stone is then
whirled in a vertical circle. If the breaking strength of the cord in tension is 70 N,
find the angular velocity at which the cord will break.
A. 23.5 rpm C. 26.8 rpm
B. 19.2 rpm D. 35.2 rpm

6. A bullet of mass 2 grams, traveling at 500 m/s is fired into a ballistic pendulum of
mass 1 kg suspended from a cord 1 m long. The bullet penetrates the pendulum
and emerges with a velocity of 100 m/s. Through what vertical height will the

T
pendulum rise?
A. 2.18 cm C. 2.89 cm

N
B. 3.26 cm D. 3.38 cm

7. Find the kinetic energy of a 25 kg wheel rotating at 6 rps if the radius of gyration

OI
if the wheel is 22 cm.
A. 0.63 kJ C. 0.90 kJ
B. 0.74 kJ D. 0.85 kJ
SP
8. A skier is filmed by a motion picture photographer who notices him traveling
down a ski run. The skier travels 36 ft during the fourth second of the filming and
48 ft during the sixth second. What distance did he cover in the eight seconds of
filming? Assume that the acceleration is uniform throughout.
A. 302 ft C. 310 ft
B. 297 ft D. 312 ft
ES

9. How high above the table should a 100 mm diameter billiard ball be struck by the
cue ball so that it will roll without friction?
A. 68 mm C. 66 mm
B. 72 mm D. 70 mm
C

10. A speed boat traveling at 30m/s is 100m from a buoy and decelerates at 3.5
m/s^2. What time it will reach the buoy?
AC

A. 21.56 s C. 4.53 s
B. 3.54 s D. 12.56 s

11. Two workers pull horizontally on a heavy box, but one pulls twice as hard as the
other. The larger pull is directed at 25° west of north, and the resultant of these
two pulls is 350 N directly northward. Find the magnitude of the smaller pull.
A. 149 N C. 159 N
B. 152 N D. 144 N

PAGE 2
 12. A car starts from rest and has a constant acceleration of 3m/s^2. What is the
average velocity during the first 10 seconds?
A. 12 m/s C. 14 m/s
B. 13 m/s D. 15 m/s

13. A 5kg mass drops 2 m upon a spring whose modulus is 10N/mm. What will be
the speed of the block when the spring is deformed 100 mm?
A. 4.6 m/s C. 5.2 m/s
B. 6.1 m/s D. 5.8 m/s

T
14. A truck weighing 1.4 kN moves up a slope of 15°. What is the force generated by

N
the engine if the truck is accelerating at a rate of 3 m/s^2? Assume the coefficient
of friction is µ = 0.1.
A. 876 N C. 930 N

OI
B. 926 N D. 958 N

15. An archer aims his bow upward and pulls the string of his arrow with a force of
80N. The strings make an angle of 25° with the vertical. Find the tension in the
SP
string.
A. 88 N C. 22 N
B. 44 N D. 33 N

16. A cantilever box beam 3m long has a cross-section that is 140 mm by 200 mm in
total dimension and is made of 30 mm thick plates. What is the maximum
ES
concentrated load that can be applied at the free end if the flexural stress is not
to exceed 70 MPa.
A. 19.47 kN C. 16.35 kN
B. 20.53 kN D. 17.53 kN
C

17. A wood cantilever 12 m high has a 20 cm diameter at the bottom and a 10 cm

diameter at the top. If the breaking stress is 35 MN/m^2, find the applied force at
the failure point.
AC

A. 1933 N C. 1399 N
B. 1393 N D. 1339 N

18. The Poisson’s ratio for a homogeneous bar is 1/3. If the bar is subjected to a
tensile load, the strain developed is 1/800. Find the change in volume per unit in
the material.
A. 1/2400 inc C. 1/1200 inc
B. 1/2400 dec D. 1/1200 dec

PAGE 3
 19. The maximum shear stress in a beam with a rectangular cross-section of breadth
b and depth h with maximum shear value V is given,
A. 3V/bh C. bh^3/12
B. 3V/2bh D. 4V/3bh

20. Hexagonal nuts for 6.25 mm diameter bolts have a height of 5.5 mm. If the
ultimate strength of the nut material in shear is 103 MPa, what is the most nearly
the maximum allowable shear force on the nut thread using a safety factor of 5?
A. 0.72 kN C. 1.0 kN

T
B. 0.8 kN D. 1.1 kN

N
21. A helical spring is made of 20 mm diameter steel wire of 20 turns on a mean coil
diameter of 160 mm. If subjected to a tensile load of 2 kN, find the maximum
stress in the spring in MPa.

OI
A. 112 C. 211
B. 121 D. 126

22. How much water overflows when a Pyrex vessel filled to the brim with 1 L of
SP
water at 20°C is heated to 90°C? The coefficient of volume expansion of Pyrex
and water are 9x10^- 6/°C and 2.1x10^-4/°C respectively?
A. 1.41 cc C. 11.4 cc
B. 14.1 cc D. 1.14 cc

23. A 200-meter cable is suspended vertically. At any point along the cable, the
ES
strain is proportional to the length of the cable below the point. If the strain at the
top of the cable is 0.001, determine the total elongation of the cable.
A. 0.05 m C. 0.15 m
B. 0.10 m D. 0.20 m
C

24. A steel ring is rotated about its diameter until the stress becomes 140 MPa. Find
the peripheral velocity.
A. 331.5 m/s C. 135.3 m/s
AC

B. 313.5 m/s D. 133.5 m/s

25. A circular rod is stretched by a force of 3 kN. Solve the diameter of the rod if the
stress is not to exceed 153 MPa.
A. 12 mm C. 10 mm
B. 8 mm D. 5 mm

PAGE 4
 26. A structural material has a modulus of elasticity of 8 x 10^6 psi and a modulus of
rigidity of 3.2 x 10^6 psi. Find the value of the Poisson's ratio.
A. 0.40 C. 0.25
B. 0.35 D. 0.30

27. How many grams are represented in 2.50 mol of H₂O?

A. 45.0 C. 43.9
B. 21.7 D. 32.7

T
28. Calculate the molality of alcohol in an aqueous solution if the mole fraction of the
alcohol is 0.150.

N
A. 9.6 m C. 9.2 m
B. 9.4 m D. 9.8 m

OI
29. An atom of beryllium consists of 4 protons, 5 neutrons, and 4 electrons. The
mass number of this atom is.
A. 13 C. 8
B. 9 D. 5
SP
30. The molality of a solution of ethyl alcohol (C₂H₅OH) in water is 1.54 mol/kg. How
many grams of alcohol are dissolved in 2.5 kg of water?
A. 192 C. 177
B. 188 D. 162
ES
31. How many atoms of hydrogen atoms are present in 2.00 molecules of ammonia?
A. 2 C. 6
B. 3 D. 8

32. How many liters of 2 M solution can be produced from 184 g of ethyl alcohol
C

CH₂CH₂OH?
A. 1.5 L C. 2.5 L
B. 2.0 L D. 5.0 L
AC

33. The density of nitrogen is 1.25 kg/m^3 at STP. Determine the density of nitrogen
at 42°C and 730 mm mercury.
A. 1.40 kg/m^3 C. 1.90 kg/m^3
B. 1.04 g/m^3 D. 1.09 kg/m^3

PAGE 5
 34. What is the pressure of 4.87 g of hydrogen H₂ that occupy 6.8L at 10°C?
A. 7.56 atm C. 7.72 atm
B. 6.93 atm D. 8.31 atm

35. What mass in grams of solute is needed to prepare 3.5 L of 400 M NaOH?
A. 54 C. 52
B. 56 D. 58

36. What is most nearly the combined volume of 1.0 g of hydrogen gas (H₂) and 10.0

T
g of helium gas (He) when confined at 20°C and 5 atm?
A. 10 L C. 14 L

N
B. 12 L D. 16 L

37. A bicycle tire has a volume of 600 cm^3. It is inflated with CO₂ to a pressure of

OI
5.4 atm at 20°C. Approximately how many grams of CO₂ are contained in the
tire?
A. 3.8 g C. 6.0 g
B. 4.8 g D. 6.4 g
SP
38. What is the rms speed of nitrogen molecule N₂ in the air at 300 K?
A. 498 m/s C. 517 m/s
B. 508 m/s D. 521 m/s

39. Two tubes are mounted to the roof of a car. One tube points to the front of the car
ES
while the other points to the rear. The tubes are connected to a manometer filled
with a fluid of specific gravity of 0.62. The density of air is approximately 1.202
kg/m^3. When the height difference is 75 mm, what is the car's speed?
A. 11 m/s C. 28 m/s
B. 15 m/s D. 96 m/s
C

40. A garden hose fills a 32 L wastebasket in 120 seconds. The opening at the end
of the hose has a radius of 1cm. How fast is the water traveling as it leaves the
AC

hose in m/s.
A. 0.63 C. 0.50
B. 0.85 D. 0.38

41. The pressure inside a 4-cm diameter hose is 700 kPa. If the water exits through
a 2-сm nozzle, what velocity in m/s can be expected inside the hose?
A. 20.42 C. 16.31
B. 12.14 D. 9.66

PAGE 6
 42. A calibrated flask has a mass of 30 g when empty, 81 g when filled with water,
and 68 g when filled with oil. Find the density of the oil.
A. 510 kg/m^3 C. 745 kg/m^3
B. 636 kg/m^3 D. 568 kg/m^3

43. A jet of water is discharged through a 1-inch diameter orifice under a constant
head of 2.1 ft. The jet is observed to pass through a point 2 ft downward and 4 ft
away from the vena contracta. Compute the coefficient of velocity.
A. 0.893 C. 0.783

T
B. 0.976 D. 0.912

N
44. Determine the velocity of the liquid which is 1.5 m deep at the exit on the side of
a tank which is 0.3 m above the base.
A. 1.9 m/s C. 3.9 m/s

OI
B. 2.9 m/s D. 4.9 m/s

45. What most nearly is the friction factor for flow in a circular pipe where the
Reynolds number is 1000?
SP
A. 0.008 C. 0.08
B. 0.06 D. 0.1

46. A circular window with a radius of 0.25 m has its center 3m below the water
surface. The window is vertical. What is most nearly the force acting on the
window?
ES
A. 2.9 kN C. 18 kN
B. 5.8 kN D. 29 kN

47. What is most nearly the overturning moment per unit width of the dam due to 3 m
of water acting on the vertical face of the dam?
C

A. 15 kN-m C. 44 kN-m
B. 30 kN-m D. 72 kN-m
AC

48. What is most nearly the minimum required force per unit width of the dam due to
3 m of water acting on the vertical face of the dam to prevent the dam from
sliding?
A. 15 kN C. 44 kN
B. 30 kN D. 72 kN

PAGE 7
 49. A reservoir dam holds an 8 sq. km lake behind it. Just behind the dam, the lake is
12 m deep. What is the water pressure at the base of the dam?
A. 118 kPa C. 125 kPa
B. 181 kPa D. 132 kPa

50. What is the hydraulic radius of the semicircular channel with a radius of 4 m?
A. 2 m C. 4 m
B. 3 m D. 6 m

T
- - - - - - - - - - - - - - - - - - - - - - - - NOTHING FOLLOWS - - - - - - - - - - - - - - - - - - - - - - -

N
OI
SP
C ES
AC

PAGE 8