MC	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

Classify each of the following according to the type of potential energy. Write the letter of the correct response to the left of the number.

1. Water in a reservoir behind a dam.

2. Hydrogen found within the sun.

3. Batteries for a CD player.

4. A bungee cord, when the jumper is at the lowest position, and the cord is stretched.

5. Rubbing a balloon through your hair, then holding it a few centimeters to the side of your hair.

Correct Answer:

1. a

2. e

3. c

4. b

5. d

MC	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

Match the following examples that best describes the energy situation. (1pt each)

a. Potential Energy

b. Kinetic Energy

c. A combination of potential Energy and Kinetic Energy

___1. When positive and negative charges are

separated from one another in a capacitor.

___2. Water stored behind a dam.

___3. A pendulum at the bottom of its swing.

___4. A skier sliding down a hill.

___5. A stretched scale spring.

___6. A vibrating spring.

___7. A flywheel that is spinning.

Correct Answers:

1. a

2. a

3. b

4. c

5. a

6. c

7. b

MC	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

What is the type and amount of energy in a wrecking ball weighing 100 pounds suspended 100 feet above the ground?

a. Accumulative energy of 1,000 lbs/ft

b. Floatational energy of 1,000 lbs

c. Kinetic energy of 5,000 ft. lbs

d. Potential energy of 10,000 ft. lbs

e. Weight energy of 10,000 lbs

Correct Answer: d

I	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

Following are six examples of kinetic and potential energy. Carefully analyze each image in order to answer the following five questions.

Pneumatic power wrench Electric-motor power saw Auto suspension spring

and shock absorber

Conveyor system Water tower Electric batteries

1. The water tower and batteries can be categorized with which other image representing potential energy?

a. Pneumatic wrench

b. Conveyor system

c. Power saw

d. Shock absorber

2. If an electrical generating turbine were added to one of the examples, which form of potential energy might power the electric saw?

a. The conveyor system

b. The shock absorber

c. The water tower

d. The power wrench

e. The batteries

3. If an air compressor were attached to the power wrench, which of the following would occur?

a. The potential energy in the compressor would all become kinetic energy in the wrench.

b. The wrench would not be able to do as much work out as the work in from the compressor.

c. The wrench will do more work than the compressor can input.

d. The kinetic energy stored in the compressor will make the wrench work.

4. How could you increase the potential energy of the water in the tower?

a. Increase the height of the tower.

b. Increase the pipeÍs diameter.

c. Increase the number of filters in the water tank.

d. Increase the valve opening at the end of the pipe.

5. What is the potential energy of the spring in the suspension system based on?

a. The kinetic energy of the car

b. The amount of air pressure in each tire

c. The springÍs speed

d. The spring height

e. The spring constant

Correct Answers:

1. d

2. c

3. b

4. a

5. e

I	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

Data showing typical ball speeds and striker speeds for different sports:

Ball	Ball mass	Ball velocity		Striker velocity		Impact time
	(kg)	(m/s) before	(m/s) after	(m/s) after	(m/s) before	(ms)
Tennis ball	0.058	0	51	38	33	4.0
Squash ball	0.032	0	49	44	34	3.0
Hand ball	0.061	0	23	19	14	1.4
Golf ball	0.046	0	69	45	32	8.0
Football kick	0.42	0	28	18	12	8.0
Cricket ball	0.16	0	39	31	27	1.4

(Data taken from : Physics, R. Hutchins, University of BATH, Thomas Nelson & Sons Ltd., 1992)

1. Find the kinetic energies of each ball just after it is struck. (12pts)

2. Find the loss in kinetic energy of the golf driver as it hits the golf ball. (2pts)

Correct Answers:

1. Use K.E. = 1ò2 mv2

75 J, 38 J, 16 J, 110 J, 165 J, 122 J (2pts each correct answer and set up)

2. Use K.E. = 1ò2 mv2final - 1ò2 mv2initial

K.E. = 122 J (1pt for answer and 1pt for set up)

P	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

During an experiment a group of Physics students drop a 0.250 kg ball from a lab table. Using a Photogate timer for several readings they find that it took the ball an average of 0.306 seconds to hit the floor.

1. What is the velocity of the ball just before it hit the ground? (3 points)

2. Find the change in kinetic energy of the ball? (3 points)

Correct Answers:

1. v=gt = (9.81 m/s2)(0.306 seconds) = 3.00 m/s

(1 point for correct equation, 1 point for the correct answer, and 1 point for the correct units)

2. KE = KE Æ KE ; 1.13 J

(1 point for the equation, 1 point for the correct answer, and 1 point for the work energy equation)

P	Physics	Standard: 04
Objective: 01. Determine kinetic and potential energy in a system.
ILO:

An airplane drops 400 m to escape some freezing rain. If it maintained the same speed but lost 200,000,000 J of energy:

1. How much PE did it lose?

2. How much KE did it lose?

3. What is the planeÍs mass?

4. Since the total energy of the system doesnÍt seem to be conserved, explain where the 200,000,000 J went.

Correct Answers:

1. 200,000,000 J

2. 0 J

3. 51,000 kg

4. Air friction

Scoring Guide:

1 point for each correct answer

Total: 4 points