Finding velocity from photogate times in collision lab

[Jeph]

I'm doing a lab were we used photogates to calculate the time before and after the collision.

I have an initial Photogate Time and a Final Photogate Time..

Working in excel I need to caculate the velocity final and initial using those times. I also need to find KEi KEf Pi and Pf.

I've dervived how to find KEi (1/2(830) vi^2, KEf (1/2(1160)Vf^2), Pi (830*Vi), Pf (1160* Vf)

for when Ma >> Mb

I don't know why I just can't seem to figure how to calculate Vi and Vf using the photogate values. please help!

 

[Jeph]

I think I might have got it..

for Vi.. is it just delta(x) (or the diameter of the cars rod that passes through the photogate) divided by the first time, for initial and the second time for final?