Question

A dumb bell consists of two identicasl small balls offmss 1/2 kg each connected to the ends of a 50 cm long light rod. The dumb bell is rotating about a fixed axis through the centre of the rod and perpendicular to it t an angular speed of 10 rad/s. An impulsive force of average magnitude 5.0 N acts on one of the masses in the direction of its velocity for 0.10s. Find the new angular velocity of the system.

Answer 1

Correct Answer - A::B::D
`tau=Ia`
`rarr Fxr=(mr^2+mr^2)alpha`
`rarr 5x0.25=2mr^2xxalpha`
`rarr alpha=1.25/(2xx0.5xx0.025xx0.25)`
=20
`omega_0=10rad/s `
`t=0.10sec`
`omega=omega_0+alphat`
`- omega=10+0.10x20`
`=10+2=12rad/s