I'm currently trying to learn kinematics and I can't figure out what seems to be a basic problem. It is the following: An 1800 kg car brakes from 15 m/s to a stop in 3 seconds. What is the net force of friction on the tires?
If you could help describe how I could figure this out or give me hints I would be very happy. Thanks :D!
in SI units;
Suppose tires give constant force so acceleration is constant:
acceleration = (0-15)m/s/3s = -5m/s^2; force = acceleration * mass = -5*1800 = -9000 Newton
check 1: acceleration is about -0.5g so force is about -0.5*1800 kilopond = -900 kilopond = about -9000 Newton
check 2: friction is about half weight of car so friction coefficient has to be at least 0.5, table says this is possible if road is dry