Coefficient of Restitution Lab
Drop balls of 6 materials (superball to clay) and measure bounce height to calculate e = √(h_bounce/h_drop). Compare energy lost per bounce.
HOW "BOUNCY" IS IT?
The Coefficient of Restitution () is a measure of how much kinetic energy is retained after a collision. It is defined as the ratio of the final relative velocity to the initial relative velocity. An means a perfectly elastic collision, while means the objects stick together (perfectly inelastic).
THE CORE FORMULA
e = \frac{|v_{2f} - v_{1f}|}{|v_{2i} - v_{1i}|}\n\nFor a ball bouncing off a floor:\ne = \sqrt{\frac{h_{bounce}}{h_{drop}}}\n\nWhere is the height.
HOW TO USE THIS VISUALIZATION
1. **Set the Coefficient**: Adjust the slider from 0 to 1.\n2. **Drop the Ball**: Watch it bounce and observe the loss in height.\n3. **Analyze Energy**: Check the kinetic energy before and after each impact.\n4. **Vary Surface**: Switch materials (rubber, steel, lead) to see typical values.
CORE FORMULAS
AP EXAM CONNECTION
Unit: Unit 4: Linear Momentum (Topic 4.2)
Learning Objective: 3.2.1
COMMON MISCONCEPTIONS
- Thinking can be greater than 1 (it would mean the collision added energy).
- Confusing with the percentage of energy retained (it's velocity-based).
- Forgetting that is a property of the *pair* of materials, not just one.
KEY TAKEAWAYS
- measures collision elasticity.
- : Perfectly Elastic.
- : Perfectly Inelastic.
- Square root of height ratio for floor bounces.
PRACTICE QUESTIONS
Q1 (QUANTITATIVE): If a ball is dropped from 1 meter and bounces to 0.64 meters, what is the coefficient of restitution?
Show Answer & Explanation
Answer: 0.8
Explanation: .
