Lesson 18 Potential and Kinetic Energy TCAP Coach Science Chapter 4 Lesson 18 Potential and Kinetic Energy TCAP Coach

Potential and Kinetic Energy Energy is the ability to make things move or cause change. Energy has many different forms, such as heat, light, sound, and the energy of moving objects. But all energy can be put into two groups- potential and kinetic energy.

Potential and Kinetic Energy Kinetic energy is the energy of motion. Potential energy is stored energy. Either of these kinds of energy can change into the other kind.

Potential and Kinetic Energy One form of potential energy is the energy of position. Picture a rock resting on top of a hill. The rock is not moving. But it could move if you gave it a shove over the edge of the hill. Because the rock is in a position where it could move, it has potential energy. Because it is not moving, it does not have kinetic energy. You give the rock a shove and it tumbles down the hill. Its potential energy changes into kinetic energy. As it moves, more and more of its potential energy is changing into kinetic energy. Near the bottom of the hill, the rock has the most kinetic energy and the least potential energy.

Potential and Kinetic Energy The higher an object is above Earth’s surface, the greater is the object’s potential energy. A rock at the top of a hill 100 meters high has more potential energy than the same rock on top of a hill 20 meters high. When the rock falls, its potential energy changes to kinetic energy. So a rock has more kinetic energy if it falls 100 meters than if it only falls 20 meters.

Potential and Kinetic Energy You can think of potential energy as money up put in a bank. By putting your money in a bank, you store it. That is like potential energy. If you take the money out of the bank, you can use it to do things, such as buy food or clothing. That is like kinetic energy. The more money you store in the bank, the more it can do when you take it out.

Potential and Kinetic Energy

Kinetic Energy into Potential Energy Just as potential energy can be changed into kinetic energy, kinetic energy can be changed into potential energy. Suppose a rock is resting at the bottom of a hill. You pick it up and toss it to the top of the hill. As the rock moves upward, it slows down. It seems to be losing energy. But what is really happening is that its kinetic energy is changing into potential energy. When the rock lands on top of the hill and stops moving, all of its kinetic energy has been changed to potential energy. The rock now has stored energy because of its position on the top of the hill.

Kinetic Energy into Potential Energy When potential energy is changed into kinetic energy, no energy is lost. The same is true when kinetic energy is changed into potential energy. The energy is in a different form, but it is the same amount of energy. Think of potential energy as 10 dimes. Then think of kinetic energy as 4 quarters. Potential =Kinetic, just as 4 quarters=10 dimes. The both equal one dollar.

Kinetic Energy into Potential Energy You can go to a bank or store and change 10 dimes into 4 quarters. You can also change 4 quarters into 10 dimes. But in changing them, you do not lose any money. Your total amount still equals 1 dollar.

Other Changes in Potential and Kinetic Energy Your body stores energy it gets from food. Some of the energy is stored in a layer of fat under your skin. In other words, the layer of fat holds your potential energy. Your body changes that stored energy into the energy of motion when you exercise.

Other Changes in Potential and Kinetic Energy Many cameras and carpenters’ tolls run on rechargeable batteries. The batteries store energy. That potential energy can be changed into electrical energy to run the cameras and the tools. Electrical energy is a form of kinetic energy. Ordinary dry-cell batteries, store energy, too. When you turn on a toy that uses batteries, the toy moves. The potential energy in the batteries changes to the energy of motion.

Other Changes in Potential and Kinetic Energy Gasoline also holds potential energy. When gasoline is burned in a car’s engine, the energy stored in the gasoline is released. That energy makes the car move. It gives the car kinetic energy. A stretched rubber band has potential energy. When you let go of the rubber band, the potential energy is changed to kinetic energy.

1. The energy stored in a battery is A. potential energy B. kinetic energy C. heat energy D. light energy

1. The energy stored in a battery is A. potential energy

2. Which of the following has the LEAST potential energy? A. a drop of water at the top of a waterfall B. a drop of water in the beginning of its drop down a waterfall C. a drop of water in the middle of its drop down a waterfall D. a drop of water near the bottom of its drop down a waterfall

2. Which of the following has the LEAST potential energy? D. a drop of water near the bottom of its drop down a waterfall

3. Any object in motion has A. potential energy B. kinetic energy C. stored energy D. light energy

3. Any object in motion has B. kinetic energy

4. Which of these changes happens when you run? A. Kinetic energy is changed to potential energy B. Potential energy is changed to kinetic energy. Energy is used up and lost. Your body makes new energy.

4. Which of these changes happens when you run? B. Potential energy is changed to kinetic energy.