# Potential and Kinetic Energy

4+

## Objective

Students will observe and record the amount of work done by marbles rolling down a plane and more fully understand the relationship between potential and kinetic energy.

## Materials

• 3 different sized marbles
• a ramp
• metre stick
• milk carton.

## Method

Can be performed as a(n) individual, group, or demonstration activity.

• Cut off the top part of a milk carton.
• Set up the ramp with the cut milk carton at the bottom (the open end of the carton should face the top of the ramp). Place a metre stick also at the bottom of the ramp beside the milk carton.
• Hold the medium sized marble at the top of the ramp. Ask students to predict how far the marble will push the carton once it gets to the bottom of the ramp.
• Let the marble go. Record the distance that the marble was able to push the carton.
• Hold the largest marble at the top of the ramp. Ask students to predict whether the marble will push the carton further or less further than the previous marble.
• Let the marble go. Record the distance that the marble was able to push the carton.
• Repeat with the smallest marble.
• Explain to students that the marble, when held at the top of the ramp, had potential energy. The energy was waiting to be used. Once the marble was let go, its energy changed into kinetic energy, moving energy. This kinetic energy was then transferred to the milk carton which caused it to also move. Additionally the heavier and larger the marble is, the more potential energy it would have, the faster it would travel, and the further the milk carton would move.
• Demonstrate the experiment again.
• Extension: Try letting the marble go at different spots on the ramp. What happens?