Question

A disc initial at rest, is rotated about its axis with a uniform angular acceleration. In the first 2s, it rotates an angle q. In the next 2s, the disc rotate through an angle –

• A. q
• B. 2q
• C. 3q
• D. 4q

Answer 1

Answer: (C)

3q

Answer 2

I = 0 + $\left[ \frac { \mathrm { ML } ^ { 2 } } { 12 } + \mathrm { M } \left( \frac { \mathrm { L } } { 2 } \right) ^ { 2 } \right]$+ [0 + ML²] = $\frac { 4 } { 3 }$ML²

Q $\frac { 1 } { 2 }$ Iw² = mgh_{CM ;} \ $\frac { 1 } { 2 } \left( \frac { 4 } { 3 } \mathrm { ML } ^ { 2 } \right) \omega ^ { 2 }$ =$3 \mathrm { Mg } \left( \frac { \mathrm { L } } { 2 } \right)$

Ž w = $\frac { 3 } { 2 } \sqrt { \frac { \mathrm {~g} } { \mathrm {~L} } }$