Physics Momentum Problem i need help fast!!

Test Preparation AP Test Preparation
1

<p>An 11900 lb railroad car traveling at 6.8 ft/s couples with a stationary car of 6690 lb. The acceleration of gravity is 32 ft/s^2.</p>

<p>a. What is their velocity after the collision?</p>

<p>b. What impulse did the first car recieve? Answer in units of lb s. Note lb s.. is basically lbs times seconds.... in case u were wondering.</p>

<p>any tips on how to get the answer for b. i think im jus screwing up on units.. i kinda need to turn it in, in like an hr.. so plz help!! thanks</p>

2

<p>Once you get the right answer for the first, the second should be trivial. Impulse is the change in momentum, so simply take M(second car)*V(final), and reverse it. Or find the difference in the momentum of the first car initially and final.</p>