Question

How much work in joules must be done to stop a 920-kg car traveling at 90 km/h?

Answer 1

Answer:

Work done, W = −287500 Joules

Explanation:

It is given that,

Mass of the car, m = 920 kg

The car is travelling at a speed of, u = 90 km/h = 25 m/s

We need to find the amount of work must be done to stop this car. The final velocity of the car, v = 0

Work done is also defined as the change in kinetic energy of an object i.e.

$W=\Delta K$

$W=\dfrac{1}{2}m(v^2-u^2)$

$W=\dfrac{1}{2}\times 920\ kg(0-(25\ m/s)^2)$

W = −287500 Joules

Negative sign shows the work done is done is opposite direction.