System of Particles and Rotational Motion - Result Question 69
76. A fly wheel rotating about a fixed axis has a kinetic energy of 360 joule when its angular speed is $30 radian / sec$. The moment of inertia of the wheel about the axis of rotation is
(a) $0.6 kg / m^{2}$
(c) $0.8 kg m^{2}$
(b) $0.15 kg m^{2}$
(d) $0.75 kg m^{2}$
[1990]
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Answer:
Correct Answer: 76. (c)
Solution:
(c) $E_r=\frac{1}{2} I \omega^{2}$
$I=\frac{2 E_r}{\omega^{2}}=\frac{2 \times 360}{30 \times 30}=0.8 kg m^{2}$
