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A wheel of moment of inertia 2 kgm^(2) ...

A wheel of moment of inertia `2 kgm^(2)` is rotating about an axis passing through centre and perpendicular to its plane at a speed `60 rad//s`. Due to friction, it comes to rest in 5 minutes. The angular momentum of the wheel three minutes before it stops rotating is

A

`24"kg m"^(2)//s`

B

`72"kg m"^(2)//s`

C

`72"kg m"^(2)//s`

D

`96"kg m"^(2)//s`

Text Solution

Verified by Experts

The correct Answer is:
C
`I=2"kg m"^(2), w_(0)=rad//s`
`t=5min=5xx60=300s`
`alpha=(0-60)/(300)=-(600)/(300)=(-1)/(5)"rad/"s^(2)` for 2 min (from (starting ) (2min =120sec)
`omega=omega_(0)+alphat`
`=60-1/5xx120=60-24`
`omega=36"rad/s" and L=Iomega=2xx36 =72"kg m"^(2)//s`
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