A car of mass 1000 kg is travelling at 20 (m/s). The car crashes into a tree, and comes to a complete halt in 0.05s. Calculate the force acting on the car during the collision.

We are asked for the force acting on the car and we know from Newton's second law that F = ma Therefore, we need to calculate the acceleration first. We use a = (vf - vo)/(t - to) where vf = final speed, vo = initial speed, t = final time and to = initial time. With all that, we have a = -20/0.05 = -400 m/(s^2)F = 1000 * (-400) = -400000 N