Question

A mass of 2 kg is moving along a circular path of radius 1 m. If the mass moves with 300 revolutions per minute, its kinetic energy would be:
1. 250 π²
2. 25 π2
3. 200 π2
4. 100 π2

Answer 1

Correct Answer - Option 4 : 100 π2

Given:

Mass (m) = 2 kg

Radius (r) = 1 m

v = 300 revolution/min

Formula used:

Angular speed (w) = 2πv

Linear speed (v) = wr

Kinetic energy = 1/2 mv²

Calculation:

v = 300/60 = 5 revolution/min 

Angular speed = 2π × 5 = 10π 

Linear speed (v) = wr = 10π × 1 = 10π 

Kinetic energy = 1/2 × 2 × 10π × 10π 

⇒ 1/2 × 2 × 100 π²

⇒ 100 π²

∴ Required kinetic energy is 100 π²