A wheel is rotating at the rate of 10 revolutions per second about an axis about which the radius of gyration is 0.2m. If the mass of the wheel is 5 kg then its rotational kinetic energy is

Options

A. 395 J
B. 295 J
C. 195 J
D. 250 J

Answer

A

Explanation

`I=Mk^(2)`
Rotational kinetic energy `=1/2 Iomega^(2)`
`=1/2Mk^(2) omega^(2)`
`:' omega=2pin`
`=2pixx10`
`=1/2xx5xx(0.2)^(2)xx(10xx2pi)^(2)`
`=10xx4pi^(2)`
`=40xx(3.14)^(2)`
`=395J`