An astronaut with a mass of #70 kg# is floating in space. If the astronaut throws an object with a mass of #8 kg# at a speed of #7/6 m/s#, how much will his speed change by?

1 Answer
Jul 25, 2017

I tried this:

Explanation:

We can use conservation of momentum before (throwing the object) and after (throwing the object) assuming that at the start the astronaut was at rest.
we get:

#0=m_("object")v_("object")+m_("astro")v_("astro")#

or:

#0=8*7/6+70*v_("astro")#

#v_("astro")=-(8*7/6)/70=-0.13m/s#

i.e. the speed of the astronaut will increase of #0.13m/s# in the opposite direction to the object.