Question

Remove both the ends from a pen so that the refill can slide freely through the barrel (Fig.). Fix the pen cap to the side of the barrel and attach a rubber band to the clip of the cap. Connect the free end of the rubber band to the refill using a safety pin. Stretch and release the rubber band. The refill shoots out, showing the conversion of elastic potential energy into kinetic energy. Repeat with different amounts of stretch, and observe how the distance travelled changes. Is there a relationship between the stretch and the distance travelled?

Answer 1

Yes, there is a relationship between the amount of stretch and the distance travelled by the refill.

When the rubber band is stretched and released, its elastic potential energy is converted into the kinetic energy of the refill. A greater stretch stores more elastic potential energy, causing the refill to move with greater speed and travel a longer distance.

• More stretch → More elastic potential energy → Greater distance travelled.
• Less stretch → Less elastic potential energy → Shorter distance travelled.

Therefore, the distance travelled by the refill increases as the stretch of the rubber band increases (within the elastic limit of the rubber band).