A 88.9 kg astronaut is working on the en-
gines of a spaceship that is drifting through
space with a constant velocity. The astronaut
turns away to look at Earth and several sec-
onds later is 30.7 m behind the ship, at rest
relative to the spaceship. The only way to re-
turn to the ship without a thruster is to throw
a wrench directly away from the ship. The
wrench has a mass of 0.502 kg, and the astro-
naut throws the wrench with a speed of 24.3
m/s.
How long does it take the astronaut to reach
the ship?
Answer in units of s.

A(n) 2.96 kg sphere makes a perfectly in-
elastic collision with a second sphere that is
initially at rest. The composite system moves
with a speed equal to one-third the original
speed of the 2.96 kg sphere.
What is the mass of the second sphere?
Answer in units of kg.