Collisions SelfCheck (Template)

Characterizing Collisions — Self-Check
Retrieval practice. Close the analysis guide and answer from memory; then check yourself. Use g = 9.81 m/s².
Name: ______________________________________ Date: __________________________________
1. Write each formula from memory
Flight interval: 𝑇𝑛 = COR from rebound heights: 𝑒𝑛 =
Peak height: ℎ𝑛 = Fraction of energy lost per bounce:
2. Calculate
Given bounce times: 𝑡1 = 0.45 𝑠 𝑡2 = 1.25 𝑠 𝑡3 = 1.97 𝑠
(a) 𝑇1 = __________s 𝑇2 = __________s
(b) Coefficient of restitution for bounce 2, 𝑒 = 𝑇2
𝑇1
= __________
(c) Rebound speed leaving bounce 1, 𝑤1 = __________m/s
(d) Peak height after bounce 1, ℎ1 = __________m
(e) Percentage of energy lost in bounce 2 = __________ %
(f) A fit gives the slope of 𝑙𝑛 𝑇𝑛 vs. n equal to −0.105. Then 𝑒 = __________
3. Explain in your own words
(a) Why does the ball reach its highest point exactly halfway through a flight interval?
(b) Why is the slope of the log plot a more reliable value of e than one pair of flight times?
Challenge. What would a flat (zero-slope) graph of 𝑙𝑛 𝑇𝑛 vs. n tell you about the collisions?