A car moving at 40 km/h is to be stopped by applying brakes in the next 4 m. If the car weighs 2000 kg, what average force must be applied on it?

Explanation

Given, u=40 km/hr
`= 40000/3600 = 11.11 m/s`
` m= 2000 kg, v=0, S=4m`,
`Acceleratio, a = (v^2-u^2)/(2S)`
` = (0^2-(11.11)^2)/(2xx4) = 123.43/8` ltBrtgt `= - 15.42 m/s^2`
(deceleration)
`:.` Breaking force, F= ma
`= 2000xx15.42`
` =30840= 3.08 xx10^4 N`.