Download Work and Energy Mini-Exam

Work and Energy
Exam
Name:_______________________
Class#:______________________
Equations you might need for this exam:
W=Fd
KE=½mv2
PE=mgh
g=10m/s2
Review True or False (1 point each)
Please circle “T” if you believe the statement is true and “F” if you believe the statement is false.
1.
T F
A hypothesis is a guess based on observations.
2.
T F
There are 100 millimeters in a meter.
3.
T F
An observation is something you think is true but can’t see.
4.
T F
Only objects that are moving have inertia.
5.
T F
A decimeter is about as long as your longest finger.
6-10 refer to this graph
distance (m)
Car # 10
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
time (s)
6.
T F
From 4 to 6 seconds this object is not moving.
7.
T F
At 10 seconds this object has moved 10 meters.
8.
T F
From 0 to 4 seconds this object is moving at a velocity of 1 m/s.
9.
T F
From 10 to 13 seconds this object is moving down hill.
10. T F
From 6 to 10 seconds this object is moving at 2 m/s.
True/False (1 Point Each)
11. T F
Potential Energy is the energy of moving objects.
12. T F
When riding a swing, your potential energy is greatest at the top of each swing.
13. T F
It takes energy to do work.
14. T F
According to the law of conservation of energy, energy would disappear if you
were driving down the road and applied your brakes to stop.
15. T F
A rock at the edge of a cliff has kinetic energy because of its position
16. T F
When you rub your hands together you convert mechanical energy to light.
Multiple Choice ( 1 point each)
Please circle the response you feel best completes/answers the item.
17. At the
a.
b.
c.
d.
top of a big hill a roller coaster has a lot of
kinetic energy (KE)
potential energy (PE)
mass
velocity
18. The kinetic energy of an object increases as its ________________ increases.
a. height
b. potential energy
c. velocity
d. gravity
19. Plants
a.
b.
c.
d.
convert
electromagnetic (light) energy to elastic potential energy
electrical energy to chemical energy
electromagnetic (light) energy to chemical energy
heat energy to mechanical energy
20. You appear to weigh less in water because
a. there is less gravity in water
b. water gives you extra energy
c. you push more water out of the way than you do air
d. the buoyant force pushes you up resisting gravity
21. For the radio to the right, you twist the crank to hear the music.
This process converts:
a. mechanical energy to thermal to nuclear
b. electric energy to sound to mechanical
c. mechanical energy to electrical to sound
d. chemical energy to mechanical to heat
Short Answer (2 pts each)
Please give your best response in complete sentences.
22. (2 pts.) Which ball in figure 5-1 has the greatest potential energy? Explain.
23. (2 pts.) Is it possible for a ball to have both kinetic and potential energy at the same time?
Explain.
24. (2 pts.) In Figure 5-1 which of the balls will have the most kinetic energy when it falls. Explain.
25. (3 pts.)The brakes on a bicycle apply 130 N of frictional force to the wheels as the
bicycle travels a distance of 10 meters. How much work was done by the brakes on the
bicycle?
26. (3 pts.) A go-cart with a mass of 50 kg is speeding down a hill at 5 m/s. How much kinetic
energy does it have?
27. (3 pts.) Some poor little girl’s brother hangs out of his second story window holding a 3 kg water
balloon at a height of 8m above her head. How much potential energy does it have?
28. (4 pts.) Describe or draw the energy changes in a swinging pendulum like the bowling ball in the
front of the room. Explain how energy does not disappear, even as a pendulum slows down
with each swing.