# Homework Help: Relative Motion of a hockey player

1. Oct 5, 2008

### wallace13

Mario, a hockey player, is skating due south at a speed of 7.1 m/s relative to the ice. A teammate passes the puck to him. The puck has a speed of 12.9 m/s and is moving in a direction of 20° west of south, relative to the ice. What are the magnitude and direction (relative to due south) of the puck's velocity, as observed by Mario?

Vpi + V mi = V pm

I basically have no idea how to even set up this problem, because i don't understand how the puck could be passed to him at 20 degrees west of south when he is going south. But I did 12.9 cos 20 = 59.64 degrees and 12.9 - 7.1 = 5.8 m/s for the velocity and its obviously wrong.

2. Oct 6, 2008

### Kurdt

Staff Emeritus
If you work out the components of velocity of the puck and subtract mario's velocity from the south component, you will then have two components of velocity of the puck from Mario's perspective and you should be able to work out the angle relative to south.