Question

The moment of inertia of a body about a given axis is 1.2 kg m². Initially, the body is at rest. In order to produce a rotational KE of 1500 joule, an angular acceleration of 25 rad/sec² must be applied about that axis for a duration of –

• A. 4 s
• B. 2 s
• C. 8 s
• D. 10 s

Answer 1

Answer: (B)

2 s

Answer 2

Q $\frac { 1 } { 2 }$ Iw² = 1500 Ž w = $\sqrt { \frac { 1500 \times 2 } { 1.2 } }$Ž 50 rad/s

\ w = w₀ + at Ž 50 = 0 + 25t Ž t = 2s