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

Answer:

$E=88200\ J$

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

$f=0.4\ties 1500\times 9.8$

$f=5880\ N$

Now from the work-energy equivalence:

$E=f.d$

$E=5880\times 15$

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