Question

the speed of car of 500 kg increased from 20 m per second to 40 m per second how much work was done by engine of the car

Answer 1

Work done = Change in Total energy.
therefore,
$w = \frac{1}{2} mu{ }^{2} - \frac{1}{2} m {v}^{2}$
On replacing values given,
$w = \frac{1}{2} .500. ({40}^{2} - {20}^{?} )$
So answer is
$w = 250.1200 = 300000j$

Answer 2

Explanation:

answer is 3×10^5...

hope it's help you