An astronaut with a mass of #85 kg# is floating in space. If the astronaut throws a #12 kg# object at a speed of #18 m/s#, how much will his speed change by?

1 Answer
Apr 14, 2018

The speed will change by #=2.54ms^-1#

Explanation:

We have conservation of momentum

#m_1u_1+m_2u_2=m_1v_1+m_2v_2#

The mass of the astronaut is #m_1=85kg#

The mass of the object is #m_2=12kg#

As the astronaut is floating in space initially,

#u_1=u_2=0ms^-1#

The speed of the object is #v_2=18ms^-1#

Therefore,

#85v_1+12*18=0#

The speed of the astronaut is #v_1=-(12*18)/(85)=-2.54ms^-1#