Question

A 1500-kg car locks its brakes and skids to a stop on a slippery horizontal road, leaving skid marks that are 15 m long. How much mechanical energy was dissipated as this happened? The coefficient of kinetic friction between the tires and the road is 400.40un.

Answer 1

`E=88200\ J`

Step-by-step explanation:

Given:

• mass of car,
  `m=1500\ kg`

• distance of skidding after the application of brakes,
  `d=15\ m`

• coefficient of kinetic friction,
  `\mu_k=0.4`

So, the energy dissipated during the skidding of car:

Frictional force:

`f=\mu_k.N`

where N = normal reaction by ground on the car

`f=0.4\ties 1500* 9.8`

`f=5880\ N`

Now from the work-energy equivalence:

`E=f.d`

`E=5880* 15`

`E=88200\ J` is the dissipated energy.