A wheel of mass 10 kg and radius of gyration 50 cm is rotating at 300 rpm. Then, the rotational kinetic energy of the wheel is

Options

A. 8 kJ
B. 6.4 kJ
C. 1.2 kJ
D. 2.2 kJ

Answer

C

Explanation

Given, M = 10 kg, K = 50 cm
`omega=300rp m`
`=(300xx2pi)/(60)"rad s"^(-1)=10 pi" rad s"^(-1)`
and `" KE = ?"`
`"Kinetic energy "=(1)/(2)lomega^(2)=(1)/(2)MK^(2)xxomega^(2)`
`=5xx25xx10^(-2)xx100pi^(2)`
Kinetic energy = 1232.45 J = 1.2 kJ