Question

The kinetic energy of a body increases from 50 J to 150 J in 10 sec. Then the power of the body is:
1. 10 W
2. 5 W
3. 100 W
4. 0 W

Answer 1

Correct Answer - Option 1 : 10 W

CONCEPT:

Work-Energy Theorem: 

• The work-energy theorem states that the net work done by the forces on an object is equal to the change in its kinetic energy.

​⇒ W = ΔKE

Where W = work done and ΔKE = change in kinetic energy

Power:

• It is defined as the rate of doing work.

\(⇒ P=\frac{W}{t}=Fv\)

Where W = work, t = time, F = force and v = average velocity

CALCULATION:

Given KE₁ = 50 J, KE2 = 150 J and t = 10 sec

By the work-energy theorem,

​⇒ W = ΔKE

​⇒ W = KE₂ - KE₁

​⇒ W = 150 - 50

​⇒ W = 100 J

So the power of the body is,

\(⇒ P=\frac{W}{t}\)

\(⇒ P=\frac{100}{10}\)

⇒ P = 10 W

• Hence, option 1 is correct.