Kinetic Energy

The Kinetic Energy MatchCard provides hands-on demonstrations and explanation of actual and potential energy.

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Using the Kinetic Emergy MatchCard

This is MatchCard #15 of the Energy Unit Study. Find more information on MatchCard Science below.

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Two Types of Kinetic Energy

Objective: Compare potential and actual kinetic energy.

There are two types of energy:

• Actual Energy: The energy of a moving object
  
• Potential Energy (or gravitational potential energy): The stored energy of a non-moving object.

So you don't think potential energy is really energy? Imagine you are standing under a heavy branch of an old oak tree that is full of snow. You start to hear a cracking sound as the weight of the snow begins to weaken the branch. Feel like moving? Could we say you have some potential energy overhead?

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Let's Experiment with Kinetic Energy

You will need the following:

• a string (yarn or tooth floss will work)
• nuts and bolts of two or more sizes/weights
• a small toy car or rolling object

Perform the following steps:

• 1. Tie one end of the string around one of the bolts.
• 2. Hold the string so that it is dangling behind the toy car which is on the floor or table.
• 3. Keep your hand holding the string steady and in the same place. Now hold the bolt and pull it so it is at a 180% angle and parallel to the floor. The string should be held tight in a straight line.
• 4. Let go of the bolt so it falls and hits the car.
• 5. Measure how far the car travels.
• 6. Repeat the steps above with the same bolt, but different sizes of string. Note that the longer the stringer, the further it falls, the faster the speed, and the greater the energy.
• 7. Repeat steps 1 - 5 again, but with different masses of bolts. (It would be idea if you have two of the same size but different masses.) The greater the mass, the greater the energy.

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Learn About the Two Types of Kinetic Energy

Gravitational Potential Energy

Potential energy is the stored energy. When you were holding the bolt, gravity gave the bolt potential energy.

In the example above, the snow-filled tree branch had potential energy. Can you think of other examples of potential energy?

• A glass of milk near the edge of a table
• A rubber band that is stretched
• A wind up toy that is wound up
• Weights on a cuckoo clock

Make a list of other examples of potential energy.

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Actual Energy

Actual energy is the energy of a moving object. It occurred as the bolt was moving.

Can you think of other forms of actual energy?

• Windmill
• Paddleboat
• Rubber band that has been released
• Avalanche

Make a list of examples of actual energy.

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The Kinetic Formula

Two factors increase the amount of energy in a moving object:

• Mass of the object
• Speed of motion

The formula for the energy of motion is:

E_K = (1/2)mv²

What's that supposed to mean?

Kinetic Energy = (1/2 the mass of an object) X (the velocity squared)

About the Root Kinet

Kinet is the Greek word for motion. That’s where we get the word for kinetics.

A kinesthetic learner is someone who learns best by physical movement. Are you a kinesthetic learner?

Kinesiology is the study of human movement. How would you like to be a kinesiologist? One of their functions is to modify equipment to make it more comfortable and practical for human use.