Correct Answer - Option 2 : 790
Concept:
Flywheel
A flywheel is used to control the variation in speed during each cycle of the engine.
The kinetic energy of flywheel can be calculated by:
K.E \(= \frac{1}{2}I{w^2}\)
where I = moment of inertia of the flywheel, ω = angular velocity of the flywheel
Calculation:
Given:
Mass of flywheel (m) = 20 kg, radius (r) = 200 mm = 0.2 m, N = 600 rpm
\(I = \frac{{m{R^2}}}{2} = \frac{{20 ~\times ~{{0.2}^2}}}{2} = 0.4\;kg - {m^2}\)
\(w = \frac{{2\pi N}}{{60}} = \frac{{2~ \times~ \pi ~\times~ 600}}{{60}} = 62.83\;rad/s\)
∴ \({\rm{K}}.{\rm{E}} = \frac{1}{2}{\rm{I}}{{\rm{\omega }}^2} = \frac{1}{2} \times 0.4 \times {\left( {62.83} \right)^2} = 789.5{\rm{\;J}} \simeq 790{\rm{\;J}}\)