Jar of Flies

jar-of-fliesA scientist weighs a jar of sleeping flies. Then, he shakes the jar to wake them up. While flies are flying in a closed jar, the scientist weighs the jar again. Does the jar weigh less when the flies are flying?

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A hockey player & referee

hockeyA 100 kg hockey player pushes a 80 kg referee with a force of 800N. Assuming they on a frictionless ice surface and the push lasts for 0.5 seconds, find the following: a) the acceleration experienced by each person b) the maximum velocity reached by each person c) do the resulting motions depend on which person instigated the pushing?   Continue reading