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A uniform circular disc of mass 400 g an...

A uniform circular disc of mass 400 g and radius 4.0 cm is rotated about one of its diameter at an anglar speed of 10 rot/s. The kinetic energy of the disc is :

A

`3.2xx10^(-5)J`

B

`1.6xx10^(-3)J`

C

`3.2xx10^(-2)J`

D

`6.4xx10^(-4)J`

Text Solution

Verified by Experts

K.E. of rotation `E_("rot")=(1)/(2)Iomega^(2)`
`=(1)/(2)((1)/(4)MR^(2)omega^(2))`
`=(1)/(8)xx400xx(4)^(2)xx(20pi)^(2)`
`=800xx400pi^(2)ergs`.
`=320000pi^(2)xx10^(-7)J`
`=32xx(3.142)^(2)xx10^(-3)`
`=3.2xx10^(-1)J`
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