A 78.0-kg tourist climbs the stairs to the top of the Washington Monument, which is 555 ft high.
How far does the Earth move in the opposite direction as the tourist climbs?
Can someone work this through for me. I have no idea where to start and I learn better when I have the problem worked out in front of me, helps me understand for future problems.
1 Answer
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Why have you mixed units in this? feet and kg are not normally compatible although in this case it really doesn’t matter.
Momentum is conserved. The centre of mass does not shift.
Moments are conserved.
So m*x = M*X
where m is the mass of the person, and M is the mass of the earth.
x is the distance that the person moves and X is the distance that the earth moves.
Note that the person actually moves slightly less than 555 feet because this is measured from the earth which has in fact moved.
but the earth moves such a tiny distance that we can ignore this difference.
so 78 * 555 = M * X
Look up the mass of the earth and complete the problem.