2.2 Potential Energy Study Guide

2.2 Potential Energy (8.2.2)

Lesson Clarity

What I will be learning.....

I will be learning about what potential energy is and how position and shape determine how much potential energy there is.

Why I will be learning this.....

I will be learning this to understand how energy is stored and transferred.  I store and transfer energy all day long, but now I will know how to explain it.

How I will know I learned it......

I will be able to define potential energy and describe the two types of potential energy, gravitational and elastic energy.
Explore this Phenomenon

1. What observations can you make about the climbers in the photo?

2. What questions could you ask to help you explore the amount of energy each one has?

8.2.2 Potential energy
Ask questions about how the amount of potential energy varies as distance within the system changes. Plan and conduct an investigation to answer a question about
potential energy. Emphasize comparing relative amounts of energy. Examples could include a cart at varying positions on a hill or an object being dropped from different
heights. Calculations of kinetic and potential energy will be learned at the high school level. 

In this section, focus on energy and matter. The transfer of energy can be tracked as energy flows through a system.

Potential Energy
Potential energy is energy that is stored in an object. Objects have potential energy because of their position or shape. The climbers have energy because of their position on the cliff. They used kinetic energy to get to that position. Now the energy is stored in the form of potential energy because of how high up the cliff they are. They have the potential to go down. If they were to fall, their potential energy would be converted to kinetic energy again.

THERE ARE TWO TYPES OF POTENTIAL ENERGY:  GRAVITATIONAL POTENTIAL AND ELASTIC POTENTIAL

Gravitational potential

 If an object has gravitational potential it can fall. Like a diver on a diving board or the skydiver from a plane, anything that is above Earth’s surface has the potential to fall because of gravity. The amount of gravitational potential energy an object has depends on the object’s mass and its distance above the ground. Between the two previous pictures the skydiver is higher above the earth and so has the greatest gravitational potential energy.

How could the child on the sled increase their potential energy?

If the gymnast increased their mass how would that affect their potential energy?

Elastic Potential
An object’s shape can also give it potential energy if when let go it tries to return to its original shape. This kind of potential energy is known as elastic potential. The girl in the photo is giving the elastic band of her slingshot potential energy by stretching it. This is known as elastic potential energy. Stretched rubber bands, inflated balloons, and springs
that are uncoiled are examples of objects that have elastic potential energy due to their shape.

How does the amount of potential energy vary as distance changes?
Think about climbers on a cliff. If one climber climbed higher than the other, how would the added distance influence the amount of potential energy involved? The
higher climber invested more energy climbing to a greater height, therefore there is more potential energy stored in the higher position. If you stretch out a rubber band on a slingshot to a farther distance it will have more potential energy because of the bigger change in shape. It also required more kinetic energy from you to pull it out
farther.

Can you think of other examples of how varying distances change the amount of potential energy involved?

Where on the roller coaster would the cart have the most potential energy?

Where would it have the least?
How is distance related to the amount of energy?

Putting It Together
1. Explain how your new understanding of potential energy helps explain the amount of energy of the people in this picture.
2. Think of another phenomenon that applies to potential energy.
3. Explain how potential energy and distance is involved in what the climbers are doing in this picture.