A Sudden Shake

Classical Mechanics Level 4

Estimate the recoil speed (in m s \frac{m}{s} ) of the Earth if the entire population of China jumped simultaneously and as high as they could. Give your answer as an order of magnitude .

I created this problem for the 2013 UBC Physics Olympics (Problem 3)


The answer is -14.

Steven Zheng by Steven Zheng , 26, China

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1 solution

Benjamin Wong
Aug 17, 2014

Earth mass: 6x10^24 kg.

Mass of all in China: (70)(1.3x10^9) = 9x10^10

Therefore earth will recoil at 1.5x10^-14 times the speed of the people's contact with the ground.

Speed of people's landing: (9.8)(0.3)=3

answer= 3(1.5x10^-14), order of magnitude =-14

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This is a mistake, by this the OoM is -13, someone correct me please

Benjamin Wong - 6 years, 10 months ago

Does it mean that we need to know the population of china...???!!!!

manish bhargao - 6 years, 3 months ago

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