Hi guys I'm completely useless when it comes to physics and need help with working something out regarding a car accident. I was rear car of a 4 car collision where all cars infront had already crashed. Now the guy infront of me is saying I shunted him which is a complete lie. I was travelling at less than 20mph when the collision happened. I want to know how fast a mass of 790kg would have to be travelling to cause a mass of 1523kg to move forward. Everyone else involved in the collision has told the truth about what happened except this clown who is trying to pull a fast one! I'll appreciate all your help!!