How High Can a Super Ball Bounce?
Students determine the coefficient of restitution (or the elasticity) for super balls. Working in pairs, they drop balls from a meter height and determine how high they bounce. They measure, record and repeat the process to gather data to calculate average bounce heights and coefficients of elasticity. Then they use data analysis and extrapolate to determine the height the ball would bounce if dropped from much higher heights.
Elasticity is a materials property we find in super balls and mattresses.Copyright (left) Wikimedia and (right) 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved. http://commons.wikimedia.org/wiki/File:Colorful_Super_ball.jpg
Mechanical engineers select materials that meet their design needs based on their properties, which might include coefficient of friction, restitution, elasticity, structural strength, melting point, etc. Scientists and engineers also need standardized ways to describe material properties and carry out repeatable experiments that take into account real-world variability that can come into play for specific measurement attempts. Scientists and engineers often need to use data analysis to extrapolate their measurements to make a prediction of what would happen under more extreme conditions. They use known patterns to make predictions (not random guesses).
After this activity, students should be able to:
- Use a ruler to measure length to the nearest cm.
- Describe that the unit of length is m and cm.
- Extrapolate using a simple number pattern (0.6 m is to 1 m as 6 m is to 10 m).