Energy & Energy Transformations



Energy & Energy Transformations Review

Learning Goals – Physical Science 3 A (PS3A)

I CAN…

• List different forms of energy (e.g., thermal, light, chemical, electrical, kinetic, potential and sound energy).

• Describe ways in which energy is transformed from one form to another and transferred from one place to another (e.g., chemical to electrical energy in a battery, electrical to light energy in a bulb).

Introduction

Energy is the ability to do work. We even say when we are tired and don’t want to work that we have low energy. Energy comes in many different forms including: heat, light, sound, electrical, kinetic (motion), potential (energy of position), and chemical. The law of the conservation of energy states that energy is never created or destroyed. However, energy can be transferred from one object to another and it can be transformed from one form of energy to another.

Energy Transformations in a Car

Energy transformations can be understood by looking no farther than a car. In the engine, the fuel (chemical energy) is burned in the cylinder. As the fuel burns, it creates hot gases (heat energy). The gases expand and press against the piston. Through a combination of rods, shafts, and gears, the piston is connected to the wheels of the car. The pressure of the expanding hot gases makes the piston move (kinetic energy). This causes the wheels to rotate and makes the car move (kinetic energy).

Not all the energy released when gasoline burns is transformed to kinetic energy. Most of it becomes heat energy. That is why the car needs a radiator to prevent it from overheating. Once the car is moving, the next important energy transformation comes when the car stops. Friction from the car’s brakes stops the car; in other words, it reduces the car’s kinetic energy. When the brake pads rub against the brake drums, the brakes get very hot (kinetic energy is being transformed to heat energy). By the time that a car stops, almost all the chemical energy stored in the fuel has been converted to heat energy.

Questions

1. Gasoline is what form of energy?

2. The moving car has what form of energy?

3. When you step on the brakes what energy transformation takes place?

Putting Wind to Work

The kinetic energy of wind starts from light energy. The light energy from the sun warms the earth’s atmosphere unevenly, causing air to move and create wind. The blades rotate like a propeller when the wind blows. The blades turn a shaft that runs into a generator, which transforms kinetic energy to electrical energy. Electricity then flows from the generator through the power lines of the local electric company and carries the energy to the user.

Putting the wind to work is a good idea for several reasons. It is environmental-friendly. No pollution! It is inexpensive. And wind is a renewable resource meaning that nature will never run out.

Questions

1. Write a short summary of how windmills convert kinetic energy of the wind to electrical energy.

2. Discuss at least two reasons why windmills are more environmentally friendly for generating electricity than methods such as nuclear, or water power (dams).

Directions Draw a line to correctly match the energy transformation description with the correct image.

1. Kinetic to Heat [pic]

2. Electrical to Light [pic]

3. Kinetic to Potential [pic]

4. Sound to Electrical [pic]

5. Electrical to Heat [pic]

Directions Match the item(s) you have been given to the correct energy transfer or transformation below.

Items: Noisemaker, Pinwheel, Glowstick, and Personal Fan

A. Item: Glowstick B. Item: Noisemaker

In the glowstick, ______________ In the noisemaker, ______________

energy is transformed to ____________ energy is transformed to _____________

energy. energy.

C. Item: Personal Fan D. Item: Pinwheel

In the battery, _____________energy In the pinwheel, _______________

is transformed to electrical energy, and energy is transferred to ______________

in the motor, electrical energy is energy.

transformed to ____________ energy.

Remember:

• Always write answers in complete sentences (Starting a sentence with “because” means it is probably incomplete.)

• Be specific! (Avoid using the word “it” as much as possible).

Directions

Using what you learned in about energy describe the energy transfer or transformations for each of the items below.

|1. Clapping Your Hands: |2. Dropping Your Pencil: |

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|3. The Toaster: |4. A Cat Lying in a Sunny Window: |

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|5. Lifting a Book Over Your Head: |6. The Radio: |

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Now come up with two of your own examples and describe the energy transfer or transformation involved in each.

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Figure 1.1 The force of the wind turns the blades which rotates the vertical shaft that is connected to a generator that transforms the kinetic energy to electrical energy.

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