Question

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

Answer 1

Given :

• Mass of the body = 20 kg
• Initial velocity of the body = 5 m/s
• Final velocity of the body = 2 m/s

To Find :

• The work done by the force

Solution :

Applying work enegy theorem ,

$\\ : \implies \sf \:W = \Delta KE$

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

Where ,

• W is work done
• m is mass
• u is initial velocity
• v is final velocity

We have ,

• m = 20 kg
• v = 2 m/s
• u = 5 m/s

Substituting the values ,

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

$\\ : \implies \sf \: W = \dfrac{1}{2} (20)(4) - \dfrac{1}{2} (20)(25)$

$\\ : \implies \sf \: W = \dfrac{1}{2} (80) - \dfrac{1}{2} (500)$

$\\ : \implies \sf \: W = 40 - 250$

$\\ :\implies{\underline{\boxed{\mathfrak{\pink{ W = - 210 \: J }}}}} \: \bigstar$