# Momentum and Collision

1. Feb 26, 2008

### ankurx13

Need some help, got a 50 question review packet of questions to finish and am having trouble with these 2. please and thank you:

1. A friend claims that as long as he has his seat belt on, he can hold on to a 12.0-kg child in a 60.0 mi/h head-on collision with a brick wall in which the car passenger compartment comes to a stop in 0.0500 s. Show that the violent force during the collision will tear the child from his arms.

2. A proton, moving with a velocity of vii, collides elastically with another proton that is initially at rest. If the two protons have equal speeds after the collision, find (a) the speed of each proton after the collision in terms of vi and (b) the direction of the velocity vectors after the collision.

2. Feb 27, 2008

### ankurx13

i would really appreciate some help guys.

3. Feb 27, 2008

### phlegmy

ok so for question 1
what you want to figure out is the force exerted by the 12kg as it decelerates from 60->0 in.05 seconds

there is a formula that says
v=u+at
which means your final velocity is equal to your inital velocity plus acceleration multiplied by time
so knowing that your final velocity is zero and time is .05 you can work out "a"