Question

2.

The Mass of a car is 1500 kg. How much work is required to be done on it to make it move with a speed of 72 km/h?

(A) 30 x 10^5 J

(B) 3 x 10^5 J

(C) 1.6 x10^6 J

(D) 30 x 10^6 J​

Answer 1

Explanation:

Answer in the attachment

Answer 2

Given:

The Mass of a car is 1500 kg.

To find:

Work is required to be done on it to make it move with a speed of 72 km/h?

Calculation:

72 km/hr = 72 × (5/18) = 20 m/s.

According to WORK-ENERGY theorem, the work done by the force will be equal to the change in Kinetic Energy of the object.

$\therefore \: W = \Delta KE$

$\implies \: W = \dfrac{1}{2} m {v}^{2} - \dfrac{1}{2} m {u}^{2}$

$\implies \: W = \dfrac{1}{2} m {(20)}^{2} - \dfrac{1}{2} m {(0)}^{2}$

$\implies \: W = \dfrac{1}{2} m {(20)}^{2} - 0$

$\implies \: W = \dfrac{400}{2} m$

$\implies \: W = 200 \times m$

$\implies \: W = 200 \times 1500$

$\implies \: W = 300000$

$\implies \: W = 3 \times {10}^{5} \: joule$

So, work done is 3 × 10⁵ Joules