1. Work, Power, and Energy Oh my!
Clicker Review
12/9/2013

2. Concept Questions Work is a form of energy. True False Question
Answer Choices
Work is a form of energy.
True
False
Work is the energy “lost” by the entity that exerts the force on an object for a distance.

3. Concept Questions True False
Answer Choices
True
False
No. Joules are units of Work just like energy. Watts are the units of Power
A Watt is the standard metric unit of work.
What is the standard unit of work and Energy?

4. Concept Questions True False Power!
Answer Choices
True
False
Power!
Work is a time- based quantity; it is dependent upon how fast a force displaces an object.
What word should replace Work?

5. Concept Questions
Question
Answer Choices
True
False
Why?
No Displacement
No Diagram
Superman applies a force on a truck to prevent it from moving down a hill. This is an example of work being done.

6. Concept Questions
Question
Answer Choices
True
False
Why?
The movement is not in the same direction as the force.
An upward force is applied to a bucket as it is carried 20 m across the yard. This is an example of work being done. F D

7. Concept Questions True False F D
Answer Choices
True
False
A force is applied by a chain to a roller coaster car to carry it up the hill of the first drop of the Shockwave ride. This is an example of work being done. F D

8. Concept Questions
Question
Answer Choices
True
False
Vice versa. If two people do the same job, then they're doing the same amount of work. The person who does it fastest generates more power.
If person A and person B do the same job but person B does it faster, then person A does more work but person B has more power.

9. Concept Questions Positive Work Negative Work No Work
Answer Choices
Rusty Nales uses a hammer to exert an applied force upon a stubborn nail to drive it into the wall.
Positive Work
Negative Work
No Work
Force diagram in same direction so is positive work F D

10. Concept Questions Gravitational Frictional Applied
Answer Choices
Which of the following is a non-conservative force?
Gravitational
Frictional
Applied

11. Which of the following statements are true about mechanical energy?
Concept Questions
Question
Answer Choices
The total amount of mechanical energy of an object is the sum of its potential and the kinetic energy.
Heat is a form of mechanical energy.
The mechanical energy of an object is always conserved.
When non-conservative forces do work, energy is transformed from kinetic to potential , but the total mechanical energy is conserved.
Which of the following statements are true about mechanical energy?

12. Concept Questions Positive Work Negative Work No Work
Answer Choices
The force of friction acts upon a baseball player as he slides into third base.
Positive Work
Negative Work
No Work
Work is done because Work and Distance are in parallel directions. Work is Negative because Work and distance are in opposite directions.

13. Concept Questions
Question
Answer Choices
Kinetic energy is the form of mechanical energy which depends upon the position of an object.
If an object is at rest, then it does not have any kinetic energy.
If an object is on the ground, then it does not have any kinetic energy.
The kinetic energy of an object is dependent upon the weight and the speed of an object.
Which of the following statements is the most true about Kinetic Energy?

14. Concept Questions
Question
Answer Choices
Moving objects cannot have potential energy.
Potential energy is the energy stored in an object due to its position.
Both gravitational and elastic potential energy are dependent upon the mass of an object.
If work is done on an object by a non- conservative force, then the object will either gain or lose potential energy.
Which of the following statements is the most true about Potential Energy?

15. Concept Questions
Question
Answer Choices
Energy, work
Power, work
Work, energy
Work, power
Power, energy
Force, work
Power, force
None of these
A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of ____, but different amounts of ____. Pick the two words which fill in the blanks in their respective order.

16. Kinetic Energy

17. Use g=10m/s2 for the following: (Kinetic Energy)
An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. When released, the arrow contains ____ Joules of kinetic energy. 50
More than 50
Less than 50
Conservation of Energy: all E transferred from GPE to KE

18. Rank the Kinetic Energy for the following from least to greatest
D<C<B<A
C<A<D<B
B<C<D<A
A<B<C<D

19. Use g=10m/s2 for the following:
A 10-Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ____ Joules.
0.5 1 10
More than 10

20. Use g=10m/s2 for the following:
An object at rest may have __________.
speed
velocity
Acceleration
Energy
All of the above

21. Use g=10m/s2 for the following: (Work-Energy Theorem)
A 50-kg platform diver hits the water below with a kinetic energy of Joules. The height (relative to the water) from which the diver dove was approximately ____ meters. 5 10 50
100
GPE=mgh
h= GPE/mg

22. Calculations:
A 51.7-kg hiker ascends a 43.2-meter high hill at a constant speed of 1.20 m/s. If it takes 384 s to climb the hill, then determine the kinetic energy change of the hiker. Delta KE = 0J

23. Calculations:
An 878-kg car skids to a stop across a horizontal surface over a distance of 45.2 m. The average force acting upon the car is 7160 N. Determine the initial Kinetic Energy of the car. KE = J

24. Calculations: (Work Energy)
An 878-kg car skids to a stop across a horizontal surface over a distance of 45.2 m. The average force acting upon the car is 7160 N. Determine the work done upon the car. W = J

25. Potential Energy

26. Rank the Potential Energy for the following from least to greatest
D<C<B<A
C<A<D<B
B<C<D<A
A<B<C<D

27. Calculations:
A 51.7-kg hiker ascends a 43.2-meter high hill at a constant speed of 1.20 m/s. If it takes 384 s to climb the hill, then determine the potential energy change of the hiker. Delta PE = 21888J GPE=mgh

28. Calculations: (Work Energy)
A 51.7-kg hiker ascends a 43.2-meter high hill at a constant speed of 1.20 m/s. If it takes 384 s to climb the hill, then determine the work done upon the hiker W = delta PE = 21888J GPE=mgh

29. Calculations: (Power)
A 51.7-kg hiker ascends a 43.2-meter high hill at a constant speed of 1.20 m/s. If it takes 384 s to climb the hill, then determine the power delivered by the hiker. P = 57 Watts P=W/t = Fd/t = Mad/t

30. Use g=10m/s2 for the following:
A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in an auto service station. Lifting the more massive car requires ____ work.
Less
The same
Twice as much
Four times as much
More than four times as much.
W=FD F=ma
W=maD

31. Use g=10m/s2 for the following:
A child lifts a box up from the floor. The child then carries the box with constant speed to the other side of the room and puts the box down. How much work does he do on the box while walking across the floor at constant speed?
Zero J
More than zero J
More information needed to determine

32. Use g=10m/s2 for the following: (Work-Energy Theorem)
A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water. 10
500
510
5000
More than 5000
Net Work= Eneregy
W = Fd = KE

33. Use g=10m/s2 for the following:
Lifting the 50 kg crate
Lifting the 25 kg crate
Both require the same amount of work.
Which requires more work: lifting a kg crate a vertical distance of 2.0 meters or lifting a kg crate a vertical distance of 4.0 meters?

34. Calculations:
Approximate the work required lift a 2.5-kg object to a height of 6.0 meters. 147 J

35. Calculations:
A 65.8-kg skier accelerates down an icy hill from an original height of 521 meters. Use the work-energy theorem to determine the speed at the bottom of the hill if no energy is lost or gained due to friction, air resistance and other non-conservative forces. 101 m/s Net W=KE Fd = .5mv2 V= square Route(KE/.5m)

36. Calculations:
Use the work-energy theorem to determine the force required to stop a 988-kg car moving at a speed of 21.2 m/s if there is a distance of 45.7 m in which to stop it.
4860 N

37. Calculations: (Work- Energy)
A 21.3-kg child positions himself on an inner-tube which is suspended by a m long rope attached to a strong tree limb. The child and tube is drawn back until it makes a 17.4-degree angle with the vertical. The child is released and allowed to swing to and from. Assuming negligible friction, determine the child's speed at his lowest point in the trajectory.
2.56 m/s

38. Calculations: (Work- Energy)
A baseball player catches a 163- gram baseball which is moving horizontally at a speed of m/s. Determine the force which she must apply to the baseball if her mitt recoils a horizontal distance of 25.1 cm. 
514 N

39. Use g=10m/s2 for the following: (Power)
P = W/t
Using J of work, a small object is lifted from the ground floor to the third floor of a tall building in seconds. What power was required in this task?

40. Calculations:
Eddy, whose mass is 65.0-kg, climbs up the 1.60-meter high stairs in 1.20 s. Approximate Eddy's power rating. 849 J P = W/t Net W=E E=GPE P=(GPE)/T P=(mgh)t