Download Work and Power and Energy Quiz

Work, Power and Energy Quiz - HP
Name: __________________________________
Multiple Choice - Identify the choice that best completes the statement or answers the question. (2pts each)
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1. In which of the following sentences is work used in the scientific sense of the word?
a. Holding a heavy box requires a lot of work.
b. A scientist works on an experiment in the laboratory.
c. Sam and Rachel pushed hard, but they could do no work on the car.
d. John learned that shoveling snow is hard work.
2. A force does work on an object if a component of the force
a. is perpendicular to the displacement of the object.
b. is parallel to the displacement of the object.
c. perpendicular to the displacement of the object moves the object along a path that returns
the object to its starting position.
d. parallel to the displacement of the object moves the object along a path that returns the
object to its starting position.
3. A more powerful motor can do
a. more work in a longer time interval.
b. the same work in a shorter time interval.
c. less work in a longer time interval.
d. the same work in a longer time interval.
4. Which of the following has the greatest power output?
a. a weightlifter who lifts a 250 N weight 2.1 m in 3.0 s
b. a mechanic’s lift that raises a 1.2  10 N car 2.1 m in 12 s
c. a car engine that does 1.2  10 J of work in 5.0 s
d. a crane that lifts a 2.5  10 N beam at a speed of 1.2 m/s
5. In which of the following scenarios is no net work done?
a. A car accelerates down a hill.
b. A car travels at constant speed on a flat road.
c. A car decelerates on a flat road.
d. A car decelerates as it travels up a hill.
_____6. Ball A has triple the mass and triple the speed of ball B. What is the ratio of the kinetic energy of ball A to ball B.
a. 3
c. 9
b. 6
d. 27
____ 7. What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
a. 54.0 J
c. 108 J
b. 87.0 J
d. 216 J
____ 8. If friction is the only force acting on an object during a given physical process, which of the following
assumptions can be made in regard to the object’s kinetic energy?
a. The kinetic energy decreases.
b. The kinetic energy increases.
c. The kinetic energy remains constant.
d. The kinetic energy decreases and then increases.
____ 9. What are the units for a spring constant?
a. N
c. Nm
b. m
d. N/m
____ 10. If the displacement of a horizontal mass-spring system was doubled, the elastic potential energy in the system
would change by a factor of
a. 1/4.
c. 2.
b. 1/2.
d. 4.
____ 11. What is the potential energy of a 1.0 kg mass 1.0 m above the ground?
a. 1.0 J
c. 10 J
b. 9.8 J
d.
96
12. A sled is pulled over level snow a distance of 200 m by a force of 150 N applied to a rope that makes an
angle of 35o with the snow in 3 minutes. How much Work is demonstrated? (3pts)
13. Work and Energy are expressed in units of Joules. Derive a Joule in fundamental units using one of the
formulas (2pts):
14. For each situation, 1) Identify at least 3 types of energy involved 2) state whether it is mechanical (M) or
non-mechanical (NM) energy, and then 3) briefly explain why that energy is involved: [4pts each]
a. A pinball machine
Type
Mechanical or Non Mechanical
Explain
b. A person running on a treadmill
Type
Mechanical or Non Mechanical
Explain
15. A spring has a force constant of 500.0 N/m. Find the potential energy stored in the spring if
it is stretched to a length of 4.1cm. (2pts)
16. A child pulls a bucket out of a 10.0 meter well at a constant velocity of 2.5m/s using a pulley. The bucket and
the water together have a mass of 21.5 kg and the pulley system causes 45N of frictional force.
a. What is the upward force in the rope being pulled by the child? (2pts)
b. How much Power is needed from the child? (2pts)
True or False: Indicate whether each of the following statements is true (T) or false (F). If False, explain and
correct your answer. If True – you are done. (2pts each)
____
17.
A car traveling at a constant speed has no work done on it.
Ex: ____________________________________________________________________
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18.
A car traveling with a speed v has kinetic energy Ek. If speed doubles, so will kinetic energy.
Ex: ______________________________________________________________________
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19.
Energy is a scalar quantity measured in Joules.
Ex: ________________________________________________________________
Work, Power and Energy Quiz -Physics
Name: __________________________________
Multiple Choice - Identify the choice that best completes the statement or answers the question. (2pts each)
____
____
____
____
____
1. In which of the following sentences is work used in the scientific sense of the word?
a. Holding a heavy box requires a lot of work.
b. A scientist works on an experiment in the laboratory.
c. Sam and Rachel pushed hard, but they could do no work on the car.
d. John learned that shoveling snow is hard work.
2. A force does work on an object if a component of the force
a. is perpendicular to the displacement of the object.
b. is parallel to the displacement of the object.
c. perpendicular to the displacement of the object moves the object along a path that returns
the object to its starting position.
d. parallel to the displacement of the object moves the object along a path that returns the
object to its starting position.
3. A more powerful motor can do
a. more work in a longer time interval.
b. the same work in a shorter time interval.
c. less work in a longer time interval.
d. the same work in a longer time interval.
4. Which of the following has the greatest power output?
a. a weightlifter who lifts a 250 N weight 2.1 m in 3.0 s
b. a mechanic’s lift that raises a 1.2  10 N car 2.1 m in 12 s
c. a car engine that does 1.2  10 J of work in 5.0 s
d. a crane that lifts a 2.5  10 N beam at a speed of 1.2 m/s
5. In which of the following scenarios is no net work done?
a. A car accelerates down a hill.
b. A car travels at constant speed on a flat road.
c. A car decelerates on a flat road.
d. A car decelerates as it travels up a hill.
______ 6. Ball A has the same mass and double speed of ball B. What is the ratio of the kinetic energy of ball A to ball B.
a. 2
c. 8
b. 4
d. 16
____ 7. What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
a. 54.0 J
c. 108 J
b. 87.0 J
d. 216 J
____ 8. What are the units for a spring constant?
a. N
c. Nm
b. m
d. N/m
____ 9. If the displacement of a horizontal mass-spring system was doubled, the elastic potential energy in the system
would change by a factor of
a. 1/4.
c. 2.
b. 1/2.
d. 4.
____ 10. What is the potential energy of a 1.0 kg mass 1.0 m above the ground?
a. 1.0 J
c. 10 J
b. 9.8 J
d.
96
11. What is the power of a kitchen blender if it can perform 3,750 joules of work in 15 seconds? (2pts)
12. For each situation, 1) Identify at least 3 types of energy involved 2) state whether it is mechanical (M) or
non-mechanical (NM) energy, and then 3) briefly explain why that energy is involved: [3pts each]
a. A pinball machine
Type
Mechanical or Non Mechanical
Explain
c. A person running on a treadmill
Type
Mechanical or Non Mechanical
Explain
13. A child pulls a bucket out of a 10.0 meter well at a constant velocity of 2.5m/s using a pulley. The bucket
and the water together have a mass of 21.5 kg and the pulley system causes 45N of frictional force.
a. Draw a force diagram to the left. (1pts)
b. Calculate the gravitational force on the bucket.((1pts)
c. What is the upward force in the rope being pulled by the child? (2pts)
d. How much Power is needed from the child? (1pts)
14. A spring has a force constant of 500.0 N/m. Find the potential energy stored in the spring
if it is stretched to a length of 4.1cm. (2pts)
15. A dog pushes his 1.5kg bone across the floor with a force of 3.2N. If he does 13.1J of Work in
doing this, how far did he push it? (2pts)
True or False: Indicate whether each of the following statements is true (T) or false (F). If False, explain and
correct your answer. If True – you are done. (2pts each)
____
16.
A car traveling at a constant speed has no work done on it.
Ex: ____________________________________________________________________
____
17.
A car traveling with a speed v has kinetic energy Ek. If speed doubles, so will kinetic energy.
Ex: ______________________________________________________________________
____
18.
Energy is a scalar quantity measured in Joules.
Ex: ________________________________________________________________