Question

The driver of a 1500 kg car, travelling on a highway, hits the brakes. A force of 12000 N stops the car in a distance of 64 m. how fast was the car going when the driver hit the brakes?

Answer 1

`v = 32 m/s`

Step-by-step explanation:

As per work energy theorem we know that work done by all the forces must be equal to change in kinetic energy of the car

So here when brakes are applied then work is done by the brakes which is equal to change in kinetic energy of the car

so we know that work done by the brakes is given as

`W = -12000 * 64`

`W = -768000 J`

now we will have

`W = 0 - (1)/(2)mv^2`

`-768000 = - (1)/(2)(1500) v^2`

`v = 32 m/s`