Hi everyone. I just finished 2 questions but I'm not sure if the answer is right. So can anyone help me check it? The first question is: "Police find the tire tracks of a car that lost control and caused an accident. They want to know if the car was speeding. They determine that μs=0.65 for it's tire on this road. The tire marks are 126m long. How fast was the car traveling?" Answer: Fcar(the force of the car) Fcar= μsFn Fn=mg Fcar= μsmg Fcar=ma ma=μsmg cross out the m a=μsg a=0.65*9.8 =6.37m/s^2 d=vt t=v/a d=v*(v/a) 126=v^2/6.37 v=28m/s The velocity of the car was 28m/s The second question is "Calculate the force acting on the body of a 60kg person who is involved in an accident. His car hits a tree while going 15m/s. The car comes to a stop with the tree embedded 1.1m into it." Answer: t=d/v =1.1m / 15m/s =0.07s a=v/t a=15m/s / 0.07s =214m/s^2 Fbrake(The force of the break) Fbrake=ma =60*214 =12840N So the force acted upon the person is 12840N I'm not really sure of question 2's answer cause it seems a bit too big.