OK, I have some homework, due soon, and could use some help. If you can give me an answer and show me how you got it, great, but I'm here to learn too. A car with a mass of 1300kg is initially moving at a speed of 40 km/h when the brakes are applied and the car is brought to a stop in 15 m. Assuming that the force that stops the car is constant, find (a) the magnitude of that force and (b) the time required for the change in speed. If the initial speed is doubled and the car experiences the same force during the braking, by what factors are (c) the stopping distance and (d) the stopping time multiplied? So there are 4 parts to this problem. I'm here to learn, but I'm also crunched for time, so any help would be appreciated.