Collisions_SelfCheck V2.docx

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) = _______s = _______s𝑇1 𝑇2
(b) COR for bounce 2, = _______𝑒 = 𝑇2
𝑇1
(c) Rebound speed, = _______m/s𝑤1
(d) Peak height, = _______mℎ1
(e) Energy lost in bounce 2 = _______ %
(f) If the slope of vs. n is −0.105, = _______𝑙𝑛 𝑇𝑛 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 vs. n tell you about the collisions?𝑙𝑛 𝑇𝑛