A ligh rod of length 1 m is pivoted at its centre and two masses of 5 kg and 2 kg are hung from the ends as shown in the figure. Find the initial angular acceleration of the rod assuming that it was horizontal in the beginning.

Answer

A, B, D

Explanation

`tau_(net)=I_(net)xxalpha`
`rarr F_1r_1-F_2r_2=(m_1r_1^2+m-2r_2^2)xxalpha`
`rarr -2xx10xx0.5+5xx10x0.5`
`=[5(1/2)^2+2(1/2)^2]alpha`
`rarr 15=7/4alpha`
`rarr alpha= 60/7=8.57rad/s^2`