Inelastic Collisions SelfCheck

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Characterizing Collisions — Self-Check
Name: ______________________________________ Date: __________________
1. Write each formula from memory (review Collision Analysis Guide if necessary, then try again –
don’t just copy from the guide)
Flight interval 𝑇𝑛 = Rebound speed 𝑤𝑛 =
COR from flight times 𝑒𝑛 = Fraction of energy lost per bounce:
2. Calculate (show your work in the box)
Given bounce times: 𝑡1 = 0.45 𝑠 𝑡2 = 1.25 𝑠 𝑡3 = 1.97 𝑠
(a) 𝑇1 = _______s 𝑇2 = _______s
(b) COR for bounce 2, 𝑒 = 𝑇2
𝑇1
= _______
(c) Rebound speed, 𝑤1 = _______m/s
(d) Peak height, ℎ1 = _______m
(e) Energy lost in bounce 2 = _______ %
(f) If the slope of 𝑙𝑛 𝑇𝑛 vs. n is −0.105, 𝑒 = _______
Height vs. time (reference)
show your work
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?