Question

The mass of a bus is 2000 kg. How much work is required to be done on it to make it move with a speed of 50 km/h?
(A) 1.6 Ã 10âµ J
(B) 1.6 à 10ⶠJ
(C) 1.93 à 10ⶠJ
(D) 193 J

Answer 1

Answer:

(c) $1.93\times 10^5$ J

Explanation:

Given,

mass of the bus, m = 2000 kg

initial speed of bus, u = 0 m/s

final speed of the bus,v = 50 km/h

                            $=\dfrac{50 \times 1000}{60\times 60}\ m/s$

                              $=\ \dfrac{50000}{3600}\ m/s$

                              = 13.88 m/s

work done on the bus = change in kinetic energy

                                   $=\dfrac{1}{2}\times m\times v^2\ -\ \dfrac{1}{2}\times m\times u^2$

                                      $=\dfrac{1}{2}\times 2000\times (13.88)^2\ -\ \dfrac{1}{2}\times 2000\times 0^2$

                                      = 192654.4 - 0

                                       $=\ 1.93\times 10^5 J$

So, the work need to be done on the bus will be $\ 1.93\times 10^5 J$