In a car crash, Car A rear ends Car B that stopped at a red light. After the crash, Car A and Car B meld together moving at a speed of 14 m/s. Car A has a mass of 1750 kg. Car B has a mass of 2000 kg.

Question

Calculate the initial momentum of Car A.

So far I have Va=?
Ma= 1750 kg
Vb=0 m/s
Mb=2000 kg
Vf=14 m/s
Pf=52500 kg m/s
Pb= 0 kg m/s

Answer 1

Okay because the cars travel together afterwards this is an inelastic collision. SO you would need the formula

Ma*Va+Mb*Vb=(Ma+Mb)Vf
because car B is at rest it can be simplified to

Ma*Va=(Ma+Mb)Vf

Now you have all the values except Va, so first solve for Va

The when you find Va you can find the momentum

Since momentum is simply p=mv; just multiply Va and Ma