Questions on momentum and collisions

[John_Locke]

Hey these could be simple questions with easy formulas and just plugging in but i don't have them my teacher is the worst teacher i have ever had in high school and what help i can get is appreciated

Homework Statement

A 68.0 kg ice skater moving to the right with a velocity of 2.99 m/s throws a 0.15 kg snowball to the right with a velocity of 22.7 m/s relative to the ground.

A second skater initially at rest with a mass of 60.50 kg catches the snowball. What is the velocity of the second skater after catching the snowball in a perfectly inelastic collision?
An 92.8 kg astronaut is working on the engines of a spaceship that is drifting through space with a constant velocity. The astronaut turns away to look at Earth and several seconds later is 28.7 m behind the ship, at rest relative to the spaceship. The only way to return to the ship without a thruster is to throw a wrench directly away from the ship. If the wrench has a mass of 0.560 kg, and the astronaut throws the wrench with a speed of 18.0 m/s, how long does it take the astronaut to reach the ship?

Homework Equations

none

The Attempt at a Solution

I don't really know where to start but i can figure out the momentum of the skaters
1) Momentum of skater is= p=mv
p=68(2.99)
P=136
Momentum of Snowball p=mv
p=.15(22.7)
p=3.405
for the Astronaut question i use Pi=Pf but i don't know how to break down the equation but i do something with the momentum of the wrench with distance and i don't know an equation for that

 

[hage567]

Look at this resource

http://hyperphysics.phy-astr.gsu.edu/hbase/conser.html#conmom

See if it helps and let us know what you come up with.

 

[John_Locke]

thanks hage good website Bookmarked it =D