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Re: [Phys-l] rich context luncheon meat



One last thing - with these results: mg = 71lb, a = .91g, t = 1.5s, T =
51lb, Peter hits the ground at over 13 m/s (30 mph).

Good catch. Actually, the issue is my own mixing of units (yet another issue to press on the students!). I solved the problem in English units, but then wrote the g-values referenced to 9.8ft/sec^2 - aack! Done correctly, the answers are:

mg = 47lb, a = .10g, t = 2.5s, T = 42lb, vfinal = 8ft/s
mg = 71lb, a = .28g, t = 1.5s, T = 51lb, vfinal = 13ft/s

The latter is equivalent to jumping off a step less than 3ft high, no? Probably OK even for a child, but you've highlighted an additional point to be made to the director :-)


Stefan Jeglinski