Question

Solve this.
Q.16. A car weighing 500 kg working against a resistance of 500 N, accelerates from rest to 20 m/s in 100 m. (g = 10 $m{s}^{-2}$). The work done by the engine of car is
(a) $1.0\times {10}^{5}J$
(b) $1.5\times {10}^{5}J$
(c) $1.05\times {10}^{5}J$
(d) None of these

Answer 1

Mass of the car, m = 500 kg

Initial velocity, u = 0

Final velocity, v = 20 m/s

Distance traveled, s = 100 m

Resistive force, f = 500 N

Using,

$v^2=u^2+2as$

$=>400=0+20\left(a\right)\left(100\right)$

$=>a=0.2m/s^2$.

Let the force applied by the engine be F.

According to the question,

$F–f=ma$

$=>F–500=\left(500\right)\left(0.2\right)$

$=>F=500+100=600N$

Thus, the work done by the engine is,

W = Fs = (600)(100) = 60000 J.

Hence, the correct option is (d): None of these.