Question

A unifrom circular disc of mass `200g` and radius `4 cm` is rotated about one of its diameters at an angular speed of `10 rad//s`. Find its abgular momentum about the axis of rotation ?

Answer 1

Here, `m= 200 g = 0.2 kg`,
`R = 4 cm = 0.04 m`.
Moment of inertia of disc about the diameter
`I = (1)/(4)MR^(2) = (1)/(4) (0.2) (0.40)^(2) = 8 xx 10^(-5) kg m^(2)`
Now, `omega = 10 rad//s`
`:. L = I omega = 8 xx 10^(-5) xx 10 = 8 xx 10^(-4) J-s`