Energy Unit Study Guide Answers

1. Energy

The ability to do work.

2. Potential Energy

Energy of rest, no motion.

5. Kinetic Energy

Energy of motion.

6. Mechanical Energy

Potential energy + Kinetic Energy

Ex: riding a bike Ex: bouncing a ball

7. Law of Conservation of Energy

Energy is neither created nor destroyed.

9. All forms of energy are a combination of

d. potential energy and kinetic energy

10. Which type of energy is transmitted by vibrations of air?

b. sound

11. When energy is converted from one form to another, what is usually produced?c. heat

12. An object’s kinetic energy is determined by its

c. mass and speed

13. Which of the following is a conversion from chemical energy to mechanical energy?

d. a person lifting a weight

14. An energy-efficient electric fan converts a large portion of the electrical energy that enters it into

b. kinetic energy of the fan blades

15. The energy in wind used to generate electricity is

d. kinetic energy

16. A skier on a hill has potential energy due to

d. position

1. At what point in the illustrations would the skater have the most potential energy? the most kinetic energy?

In illustrations A and B….. Points 1 & 5….top of the ramp hill.

2. At what point in illustration B will the skater’s kinetic energy begin to be changed back into potential energy?

Point 1 because he will not be at rest until the top of the other side of the ramp.

3. When the skater’s kinetic energy is changed back into potential energy, will this amount of potential energy likely be equal to the skater’s potential energy in illustration A?

No, because illustration A will have a stronger pendulum effect of gravitational potential energy.

4. What energy conversions produce unwanted forms of energy are occurring?

Energy seems to decrease in illustration A because the momentum slows down as the skater reaches the middle of the ramp.

Gravitational potential energy

causes unwanted forms of energy. (a person falling….loss of thermal & chemical energy)

5. Draw colored bars that might represent the potential energy and kinetic energy of the skater at each of the five labeled points on illustration A. Explain why you drew the bars the way you did.

6. How are plants and solar cells similar? How are the ways in which they capture sunlight and convert it into other forms of energy different?

Plants & solar cells use energy from the sun.

Plants = use photosynthesis to grow chemically.

Solar Cells = capture sunlight to store and use as thermal or electrical energy, etc.

7. Explain how energy sources such as solar energy and wind energy have similar problems that must be overcome. How have scientists tried to address these problems?

Not all places on Earth have alot of wind or sunlight.

Stop Thermal Pollution, use generators for electricity, solar panels and power plants.

8. Suppose that one air conditioner becomes very hot when it is working but another air conditioner does not. Which air conditioner is more energy efficient? How can you tell?

The 2nd air conditioner is more energy efficient because it is not wasting thermal energy.

9. Suppose a vacuum cleaner uses 100 units of electrical energy. All of this energy is converted into thermal and sound energy (from the motor), and into the kinetic energy of air being pulled into the vacuum cleaner. If 60 units of electrical energy are converted into thermal energy and sound energy, how much electrical energy is converted into the desired form of energy?

100 units - 60 units

40 units vacuum suckage

10. Describe a process in which energy changes forms at least twice. Draw and label a diagram

Riding a bike = chemicalkineticpotentialkinetic

Fan = electricalmechanicalsound

Light bulb = electricalthermallight