Question

Two astronauts push off of each other in space. The 80kg astronaut ends up going 10 m/s. The other one ends up going 8 m/s. What is the mass on the other astronaut?

Answer 1

We have to use conservation of momentum here.
So m1*v1=m2*v2
where m1 and m2 are masses and v1 and v2 are velocitis
We can easily tranform our formula to get m2
$m1*v1=m2*v2 \\ \frac{m1v1}{v2}=m2$
Now we can substitute our data
m2=$\frac{80*10}{8}=100$ [kg] - its our result