Question

A car seller claims that his $1000$ kg car can accelerate from rest to a speed of $24$ $m{s}^{-1}$ in just $8.0$s. Find average power of engine of the car.

Answer 1

We know Power$=\frac{workdone}{time}$------(1)

Also work done= Force$\times$ displacement

Now given at time $t=8$ seconds the maximum velocity that the car attains from rest =$24$ m/s

So acceleration$=\frac{v-u}{t}$=3 m/$s^2$

Now force= mass$\times$acceleration=$1000\times 3=3000$ N

Also from equation of motion we have,

$s=ut+\frac{1}{2}a{t}^2$

$s=96m$

Now putting the above found values in equation 1 we get

Power$=\frac{3000\times 96}{8}$

Average power=$36$ KW