- #1

discosucks

- 23

- 3

## Homework Statement

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 traveling 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

stop.

(Use g = 9.81 m/s2. You may neglect air resistance and assume level ground)

## Homework Equations

(i) F = ma

Fk = μk Fn

(ii)

Dynamic equations

## 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?

a= ?

v = 0 m/s

u =25m/s

t = ?

s=?

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 I am very confused .