A) \[8.5s\]
B) \[5s\]
C) \[2s\]
D) \[1s\]
Correct Answer: C
Solution :
Kinetic energy of rotation is half the product of the moment of inertia\[(l)\]of the body and the square of the angular velocity\[(\omega )\]of the body. Kinetic energy of rotation\[=\frac{1}{2}\times \]moment of inertia\[\times \]angular velocity i.e., \[K=\frac{1}{2}/{{\omega }^{2}}\] \[{{\omega }^{2}}=\frac{2K}{l}\] Given\[l=1.2kg\,\,{{m}^{2}},\,\,K=1500\,\,J\] \[{{\omega }^{2}}=\frac{2\times 1500}{1.2}\] \[\Rightarrow \] \[\omega =50\,\,rad/s\] From the equation of angular motion, we have \[\omega ={{\omega }_{0}}+\alpha t\] where\[{{\omega }_{0}}\]is initial angular velocity, \[\alpha \]is angular acceleration and\[t\]is time given\[{{\omega }_{0}}=0\], \[\omega =50\,\,rad/s\] \[\alpha =25\,\,rad/{{s}^{2}}\] \[t=\frac{\omega }{\alpha }=\frac{50}{25}=2s\]
You need to login to perform this action.
You will be redirected in
3 sec
