A) 10 sec
B) 8 sec
C) 2 sec
D) 4 sec
Correct Answer: C
Solution :
Here: Moment of inertia \[I=1.2\text{ }kg\text{ }{{m}^{2}}\] Rotational kinetic energy \[k=1500\text{ }J\] Angular acceleration \[\alpha =25\text{ }rad/se{{c}^{2}}\] Using the relation for the rotational kinetic energy is given by as \[KE=\frac{1}{2}I{{\omega }^{2}}=\frac{1}{2}\times 1.2{{\omega }^{2}}\] Or \[1500=\frac{1}{2}1.2{{\omega }^{2}},\] So, \[{{\omega }^{2}}=\frac{1500\times 2}{1.2},\] So, \[\omega =50\,rad/\sec \] Hence time\[T=\frac{\omega }{\alpha }=\frac{50}{25}=2\sec \]
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