Moment of Inertia - Swinging arms

[elemis]

My workings are below :

Following the calculation of w I use v=wr where r= 3 and calculate the tangential velocity.

It's then easy to see that a speed of 340 (Mach 1) will be attained in 128 s

Is this correct ?

 

[haruspex]

In your handwritten working, you've written omega instead of omega-dot, but otherwise it all looks correct.

 

[elemis]

In your handwritten working, you've written omega instead of omega-dot, but otherwise it all looks correct.

I don't understand you. Torque = Iw , correct ?

 

[hms.tech]

I don't understand you. Torque = Iw , correct ?

No, it is

τ = Iα

where α is the angular acceleration

 

[haruspex]

No, it is

τ = Iα

where α is the angular acceleration

... and although the OP says "I use v=wr ", what has actually been used is a = αr.