# Homework Help: Linear momentum experiment

1. Oct 10, 2015

### amanda.ka

1. The problem statement, all variables and given/known data
I did an experiment where I dropped a ball beneath a motion sensor and it recorded the vertical components of position vs time, velocity vs time, and acceleration vs time.
The question asks to determine the change in the ball's linear momentum (per until mass) during the 5 selected impacts with the ground. I know that the equation for linear momentum is p = (mass)(velocity) however the experiment did not say to weigh the ball so I do not have "m". How would I go about solving this? Also I know that momentum is a vector quantity so the sign is important. Does that mean my velocity values would be negative as the ball is falling towards the ground? Thanks in advance!

2. Relevant equations
p = mv

3. The attempt at a solution

2. Oct 10, 2015

### vela

Staff Emeritus
Note that the problem didn't ask you for the momentum but the momentum per unit mass.

This depends on your sign convention. Which direction do you want to call the positive direction? If the ball's velocity is in that direction, it would be positive; if it's in the opposite direction, it would be negative.

3. Oct 10, 2015

### amanda.ka

4. Oct 10, 2015

### vela

Staff Emeritus
Yes, the momentum per unit mass is just the velocity.