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Grade 11Mechanics

Plz answer the attached question....how to solve?????

Question image for Plz answer the attached question....how to solve?
Profile image of nagashravan hemadri
8 Years agoGrade 11
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1 Answer

Profile image of Arun
8 Years ago
initial kinetic energy = 1/2 I ω²  = 1/2 m r² ω²
I = moment of inertia of  hoop of radius r and mass m. = m r²
ω = angular velocity.
initially the center of mass is not moving.
let the hoop rotate and roll on the surface with an angular velocity = ω1
So its kinetic energy when it rolls = 1/2 I ω1²  + 1/2 m (rω1)²
1/2 m r² ω² =  1/2 m r² ω1²  + 1/2 m r² ω1²
ω² = 2 ω1²  =>
ω1 = ω /√2
so velocity  v = r ω1 = r ω/ 2