An astronaut with a mass of #95# #kg# is floating in space. If the astronaut throws an object with a mass of #2# #kg# at a speed of #7/8# #ms^-1#, how much will his speed change by?

1 Answer
David G.
Jun 27, 2017

The astronaut will have the same momentum in the opposite direction to the thrown object. Given his greater mass, this means his speed will change from #0# #ms^-1# to #0.018# #ms^-1#.

Explanation:

The overall momentum is zero before the object is thrown, and must be zero afterward.

The momentum of the thrown object will be #p=mv=2*7/8=14/8=7/4=1.75# #kgms^-1#.

The momentum of the astronaut will have the same magnitude in the opposite direction:

#p = 1.75 = 95*v#

Rearranging:

#v=1.75/95=0.018# #ms^-1#

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