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3A1 > 101-150 > Flashcards

101-150 Flashcards

1
Q
  1. A body having a mass of 50.97 kg is pulled along a horizontal flat surface at a constant speed by a force of 180 N, which makes an angle of +30° with the horizontal. Find the coefficient of kinetic friction for the surfaces.

a. 0.311
b. 1.441 N
c. 0.896
d. 0.38 N
e. 0.38

A

a. 0.311

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2
Q
  1. A body of a gravitational force of 2000 N is pulled along a horizontal surface at constant speed by a rope that makes an angle of 20° above the horizontal. If the pull on the rope is 150 N, the coefficient of sliding friction is:

a. 0.0257
b. 0.0275
c. 0.0275N
d. 0.0656
e. 0.0723

A

e. 0.0723

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3
Q
  1. Find the value and applied angle of the least force required to move a vessel, if the mass of the vessel is 1650 kg and the coefficient of friction is 0.49.

a. 7931 N, 26.10°
b. 5562.52N, 31.47°
c. 5522.52N, 31.47°
d. 4098.52N, 22.22°
e. 726.03N, 25.10°

A

a. 7931 N, 26.10°

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4
Q
  1. A load of 750 kg just starts to move when the friction angle is 10°. What effort must be applied parallel to the inclined surface to stop the motion of the block?

a. 7245.72 N
b. 1478.22 N
c. 1297.33 N
d. 1277.62 N
e. 1124.35 N

A

c. 1297.33 N

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5
Q
  1. A 1000 kg body is pulled along a horizontal surface at a constant speed by a rope that makes an angle of 15° above horizontal. If the pull on the rope is 150 N, the coefficient of friction is:

a. 0.14
b. 0.0148
c. 0.004
d. 0.10
e. 0.15

A

b. 0.0148

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6
Q
  1. A refrigerator is sets on a perfect level surface and has a mass of 150 kg. It is pushed by a force of 35° N acting at 30° to the supporting surface for the refrigerator. Assume that the coefficient of friction between the refrigerator and the suppoting surface is 0.25. What will happen to the refrigerator?

a. The refrigerator will start moving, then maintain steady speed as kinetic friction increases.
b. The refrigerator will slide and continue to accelerate.
c. The refrigerator will slide at a constant velocity.
d. The refrigerator will tip.
e. The refrigerator will not move.

A

d. The refrigerator will tip.

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7
Q
  1. A sliding face of a slide valve of a steam engine is 150 mm by 300 mm, and the steam pressure on the back of the valve is 1200 kN/m2. If the coefficient of friction is 0.02, what is the force required to move the valve?

a. 2400 N
b. 1800 N
c. 1080 N
d. 960 N
e. 840 N

A

c. 1080 N

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8
Q
  1. A man has a mass of 70 kg. What is the magnitude of the largest mass he can pull by a horizontal rope along a horizontal floor, if the coefficient of friction between the mass and the floor is 0.23, and that between his boot soles and the floor is 0.5?

a. 152.2 kg
b. 52.2 kg
c. 70 kg
d. 102.2 kg
e. 343.4 kg

A

a. 152.2 kg

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9
Q
  1. A block of stone of 40 kg is hauled along a horizontal floor by a force inclined 20° to the horizontal. If the coefficient of friction between the stone and the floor is 0.3, determine the effort required to just move the stone from rest.

a. 157.77N
b. 140.63 N
c. 117.72 N
d. 112.9 N
e. 84.2 N

A

d. 112.9 N

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10
Q
  1. Force of friction always?

a. Goes along with the applied force.
b. Goes against the applied force.
c. Depends on the contact area between two surfaces.
d. Harmful to the operation of machinery.
e. Exist even when there is no applied force.

A

b. Goes against the applied force.

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11
Q
  1. The relationship between the static friction and kinetic friction is as follows:

a. The static friction is always greater than the kinetic friction.
b. The kinetic friction is always greater than the static friction.
c. The static friction is twice the kinetic friction.
d. The kinetic friction is twice the static friction.
e. The relationship between static and kinetic friction depends on the nature of the contact surfaces.

A

a. The static friction is always greater than the kinetic friction.

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12
Q
  1. To increase the frictional force, it is necessary to?

a. Increase the roughness of at least one of the surfaces in contact.
b. Increase the roughness of both surfaces in contact.
c. Increase the speed of the moving body.
d. Increase of the area of surfaces in contact.
e. Apply a greater force parallel to the contact surfaces.

A

a. Increase the roughness of at least one of the surfaces in contact.

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13
Q
  1. Kinetic friction is always less than?

a. Static friction
b. Sliding friction
c. Fluid friction
d. Standing friction
e. Rolling friction

A

a. Static friction

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14
Q
  1. When the co-efficient of friction increases, and the force between the two surfaces remains constant, the friction force will?

a. Remain constant
b. Decrease
c. Increase
d. Decrease exponentially
e. Approach zero

A

c. Increase

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15
Q
  1. If an object initially at rest on a horizontal surface is pushed by a force F making 20° to the horizontal surface, then the frictional force developed between the contact surfaces is __________ as compared to when the force is applied horizontally to the body.

a. Decreased
b. No difference
c. Increased
d. Two times bigger
e. 0.342 times less

A

c. Increased

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16
Q
  1. Distance is:

a. Displacement divided by time
b. Speed multiplied by time
c. A scalar quantity
d. A vector quantity
e. Displacement multiplied by time

A

c. A scalar quantity

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17
Q
  1. Velocity:
1.     Refers to a body's speed in a certain direction
2.     Is displacement divided by time
3.     Is a vector quantity
4.     Is a scalar quantity

a. 1, 2, 3
b. 2, 3, 4
c. 1, 3, 4
d. 1, 2, 4
e. 1, 2, 3, 4

A

a. 1, 2, 3

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18
Q
  1. Displacement is:

a. A vector quantity
b. Speed multiplied by time
c. A scalar quantity
d. Acceleration divided by time
e. Velocity divided by time

A

a. A vector quantity

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19
Q
  1. Acceleration is:

a. The increase of the displacement of a body
b. A body’s rate of change of velocity
c. Expressed usually as km/h
d. The rate of change of time
e. The increase of the velocity of a body

A

b. A body’s rate of change of velocity

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20
Q
  1. Average velocity is determined by:

a. V = v/2
b. V = u + 2a s2
c. V = (u + v)/2
d. V = u - at
e. V = ut + 1/2 a t2

A

c. V = (u + v)/2

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21
Q
  1. Since the constant 9.81 m/s2 is used so frequently it is given the symbol:

a. V
b. g
c. s
d. A
e. C

A

b. g

22
Q
  1. As the acceleration due to gravity is a known constant, the final velocity of a falling body may be found by the formula:

a. V = u2 + 2a s2
b. V = u + v/2
c. V = u + at
d. V = u2+ 2as
e. V = ut + 1/2 a t2

A

c. V = u + at

23
Q
  1. Motion in a straight line is known as:

a. Vector motion
b. Slow motion
c. Linear motion
d. Scalar motion
e. Straight vertical motion

A

c. Linear motion

24
Q
  1. Distance is a scalar quantity.

a. True
b. False

A

a. True

25
Q
  1. A word, which refers to change in the position of a body, relative to some reference point is:

a. Magnitude
b. Displacement
c. Direction
d. Distance
e. Velocity

A

b. Displacement

26
Q
  1. The units of velocity are the same as the units of speed.

a. True
b. False

A

a. True

27
Q
  1. The velocity of a body is decreasing with time. It is said to be:

a. Going slower
b. Retarding
c. Accelerating
d. Genuflecting
e. Decreasing modulation

A

b. Retarding

28
Q
  1. The turning effect of a force about a point is the _______ moment of a force.

a. Last
b. Perpendicular
c. Magnitude
d. First
e. Mid

A

d. First

29
Q
  1. If a body is in equilibrium, the resultant of all forces acting upon the body must be zero.

a. True
b. False

A

a. True

30
Q
  1. From the definition, the result of a force moving through a distance is:

a. Power
b. Acceleration
c. Work
d. Moment of force
e. Velocity

A

c. Work

31
Q
  1. Energy a body acquires when in motion is referred to as?

a. Linear
b. Frictional
c. Mechanical
d. Kinetic
e. Rotational

A

d. Kinetic

32
Q
  1. The potential energy contained in a mass of 20 kg located 15 meters above ground level is:

a. 2.934 J
b. 300 J
c. 2.943 kJ
d. 30 kJ
e. 300 kJ

A

c. 2.943 kJ

33
Q
  1. A steam turbine has an output of 40 MJ/s. Its power output, in kW is?

a. 11.11 kW
b. 4 000 KW
c. 40 000 kW
d. 24 000 kW
e. 240 000 kW

A

c. 40 000 kW

34
Q
  1. In order to calculate the power in watts required to lift a 25 kg concrete block to a height of 40 m, you would also need to know the?

a. Time in seconds
b. Specific gravity of concrete
c. Mass-to-height ratio
d. Atmospheric pressure
e. Volume and density of the block

A

a. Time in seconds

35
Q
  1. The power required to drive a pump which has an output of 15 kW and an efficiency of 90% is:

a. 10.0 kW
b. 13.5 kW
c. 15.0 kW
d. 16.67 kW
e. 17.5 kW

A

d. 16.67 kW

36
Q
  1. The work required to move a mass of 20 kg up a vertical distance of 10 metres in one minute is:

a. 9.81 J
b. 32.7 J
c. 32.7 kJ
d. 1962 J
e. 115.72 kJ

A

d. 1962 J

37
Q
  1. A 1 kg pipe wrench is dropped from a height of 25 m. In kilometers per hour, its velocity at impact will be:

a. 22.15 km/h
b. 25 km/h
c. 30 km/h
d. 61.8 km/h
e. 79.7 km/h

A

e. 79.7 km/h

38
Q
  1. The quantity which describes the rate and the direction of motion is:

a. Velocity
b. Acceleration
c. Speed
d. Displacement
e. Distance

A

a. Velocity

39
Q
  1. An airplane travels 1000 km eastwards for 2 hours. Its average speed in m/sec is:

a. 69.44 m/s
b. 138.89 m/s
c. 500 m/s
d. 1000 m/s
e. 3600 m/s

A

b. 138.89 m/s

40
Q
  1. A motorcycle traveling at 30 km/h increases its velocity uniformly to 110 km/h in the time of 5 seconds, while traveling the distance of 97.2 m. Its acceleration in m/s2 is:

a. 16 m/s2
b. 7.78 m/s2
c. 4.45 m/s2
d. 28 m/s2
e. 111.15 m/s2

A

c. 4.45 m/s2

41
Q
  1. In a speed test of a car, the machine traveling at 40 km/h increases its velocity uniformly for 4 seconds, while traveling the controlled distance of 100 m. Its acceleration in m/s2 is:

a. 25 m/s2
b. 6.945 m/s2
c. 4.45 m/s2
d. 2.8 m/s2
e. 111.15 m/s2

A

b. 6.945 m/s2

42
Q
  1. By definition, the rate of change of velocity in time is called:

a. proportionality constant
b. velocity ratio
c. acceleration or deceleration
d. speed
e. velocity moment

A

c. acceleration or deceleration

43
Q
  1. A train travels at various speeds between several stations. From the train schedule the following information can be extracted about the different segments of the journey:
    8 km traveled in 10 min., 14 km in 12 min., 16 km in 18 min., 12 km in 10 min.
    The average speed during the whole trip is:

a. 13.89 km/h
b. 50 km/h
c. 60 km/h
d. 72 km/h
e. 100 km/h

A

c. 60 km/h

44
Q
  1. A flywheel changes speed uniformly from 400 rpm to 100 rpm in one (1) minute. What is the angular retardation of the flywheel in rad/s2?

a. 0.0833 rad/s2
b. 0.523 rad/s2
c. 0.698 rad/s2
d. 1.0 rad/s2
e. 5.0 rad/s2

A

b. 0.523 rad/s2

45
Q
  1. Speed is known as the ______________________.

a. rate of change of displacement
b. rate of change of velocity
c. a scalar quantity
d. a vector quantity
e. None of the above

A

c. a scalar quantity

46
Q
  1. The kinetic energy of a 1000 kg automobile traveling at 60 km/h is:

a. 16.67 kJ
b. 60 kJ
c. 138.8 kJ
d. 60 000 kJ
e. None of the above

A

c. 138.8 kJ

47
Q
  1. The hammer of a pile driver has a mass of 3 000 kg. It falls through a height of 9 m. The hammer’s kinetic energy just before impact is:

a. 27.0 kJ
b. 264.87 kJ
c. 27 000 kJ
d. 243 000 J
e. None of the above

A

b. 264.87 kJ

48
Q
  1. From what height must a mass of 2 kg fall to have the same amount of kinetic energy as a bullet of 25 g traveling at the speed of 1000 m/s.

a. 50 m
b. 98.1 m
c. 243.7 m
d. 543.39 m
e. 637.1 m

A

e. 637.1 m

49
Q
  1. The internal resistance to an external force applied to a body is known as:

a. Strain
b. Stress
c. Young’s Modulus
d. Ultimate strength
e. Allowable strength

A

b. Stress

50
Q
  1. When referring to stress as used in applied mechanics, the value is usually expressed in:

a. Kilopascals
b. Kilowatts
c. Joules
d. Square metres
e. Newton/metres

A

a. Kilopascals

3A1 (12 decks)

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