Question

Certain force acting on a 20 kg mass changes its velocity from 5m/s to 2m/s . Calculate the work done by the force.​

Answer 1

Answer:

The work done by the force is -210 Joules.

Given:

• Mass of an object, m = 20kg
• Initial velocity of an object, u = 5 m/s
• Final velocity of an object, v = 2 m/s

To Find:

• The work done by the force.

Formula Used:

${\underline{\boxed{\bf Work\:done\:by\:force\: = \dfrac{1}{2} mv^2 - \dfrac{1}{2} mu^2}}}$

Where,

• m = mass of an object.
• v = final velocity.
• u = Initial velocity.

Solution:

According to the question,

Work done by force = Change in KE.

Work done by force = $\sf \dfrac{1}{2} mv^2 - \dfrac{1}{2} mu^2$

$: \implies \sf \dfrac{1}{2} \times m(v^2 - u^2)$

$: \implies \sf \dfrac{1}{2} \times 20 (2^2 - 5^2)$

$: \implies \sf 10 (4-25)$

$: \implies \bf Work\:done\: = -210 J$

$\therefore$ Work done by the force is -210 J.