Question

4 A car moves at a constant velocity of 30 m/s and has 3.6 x 10*5J of kinetic

energy. The driver applies the brakes and the car stops in 95 m.
Calculate the force needed to stop the vehicle.

Answer 1

To find the force we need mass and acceleration so let's find them first

`(1)/(2) m {v}^(2) = 3.6 * {10}^(5) \\ (1)/(2) * m * 900 = 3. {10}^(5) \\ m = 800kg`

`{v}^(2) = {u}^(2) + 2as \\ 0 = 900 - 2a(95) \\ a =4.7m {s}^( - 2)`

`f = ma \\ f= 800 * 4.73 \\ f= 3784n`