A motorcar is moving with a velocity of 108 km `h^(-1)` and it takes 4s to stop after the brakes are applied .Calculate the force exerted by the breakes on the motorcar if its mass along with the passengers is 1000 kg.

Explanation

The initial velocity of the motorcar
u=108 `h^(-1)`
`108xx1000m/(60xx60s)`=
30 m`s^(-1)`
And the final velocity of the motorcar
v=0 ,`ms^(-1)`
and the final velocity of the motorcar
v=0 m`s^(-1)`
The total mass of the motocar along with its passegers m=1000 kg and the tiime taken to stop the motorcar,t=4s
Magnitude of the force (F) applies by the brakes as `(m(v-u))/(t)`
On substituting the values,we get
`F=(1000kgxx(0-30)ms^(-1))/(4s)` The negative sign tell us that the force exerted by the brakes is opposite to the direction of motion of the motorcar.