Question

Certain force acting on a 20 kg mass changes its velocity from 5ms -1 to 2ms -1 .
Calculate the work done by the force

Answer 1

Given,

• Mass = 20kg
• Initial velocity = 5ms -1
• Final velocity = 2ms -1

To Find:-

Work done by the force.

Formula used:-

$w = \frac{1}{2} {mu}^{2} - \frac{1}{2} {mv}^{2}$

Calculations:-

$w = \frac{1}{2} {mu}^{2} - \frac{1}{2} {mv}^{2}$

$w = \frac{1}{2} m( {u}^{2} - {v}^{2} )$

Now,

substituting the given values

$w = \frac{1}{2} \times 20 \times ( {2}^{2} - {5}^{2} )$

$w = 10(4 - 25)$

$w = - 10 \times 21$

$w = - 210j$

Hence,the negative sign implies the retarding nature of applied force.