Just found this site ,looks really helpful , so i am doing some revision using past exam papers and have a few head scratches you guys maybe able to help with .
A car of mass 1000 kg is travelling at a speed of 25 m/s when it applies its brakes suddenly.
The car immediately skids. If the coefficient of kinetic friction between the car and the
road is 0.58, calculate:
i. the magnitude of the force of friction acting on the car during the skid
ii. the time taken from when the brakes are applied for the car to come to a complete
(Use g = 9.81 m/s2. You may neglect air resistance and assume level ground)
(i) F = ma
Fk = μk Fn
The Attempt at a Solution
so first i worked out that the force of the car is its mass (1000kg) x its acceleration (25 m/s) and that this is x the coefficient of 0.58 = 14500n
but when starting to work on the 2nd i became confused on what information i actually have . If i wanted to use one of the dynamic equations for solve the time taken to stop do i have enough to do so?
v = 0 m/s
t = ?
this led me to think that 25 m/s is not actually the acceleration like I have used it in the first part and now im very confused .