Question

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

Answer 1

Given,

• Mass (m) = 20 kg
• Initial velocity (u) = 5 m/s
• Final velocity (v) = 2 m/s

To Find,

• The work done by the force.

According to question,

According to the work = Energy theorem,

Work done = Change in kinetic energy

W = ΔK.E

W = ¹/2 m(v² - u²)

[ Put the values ]

⇒ W = ¹/2 × 20 (2² - 5²)

⇒ W = 10 × (4 - 25)

⇒ W = 10 × (-21)

⇒ W = -210 J

Therefore,

The work done by the force is -210 J.