An astronaut with a mass of #75 kg# is floating in space. If the astronaut throws a #5 kg# object at a speed of #8 m/s#, how much will his speed change by?

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Answer 1 · 2018-03-07T19:15:13

His speed change is -0.5 m/s.

Momentum is conserved.

Momentum before = momentum after

#(m_1 + m_2)*u = m_1*v_1 + m_2*v_2#

#(75 kg + 5 kg)*0 = 75 kg*v_1 + 5 kg*8 m/s#

#75 kg*v_1 = -5 kg*8 m/s#

#v_1 = (-5 kg*8 m/s)/(75 kg) = -0.533 m/s ~= -0.5 m/s#

I hope this helps,
Steve