- #1

cheapstrike

- 42

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## Homework Statement

A wheel of moment of inertia 5×10

^{-3}kg-m

^{2}is making 20 rev/s. Find the torque required to stop it in 10s is

(A) 2π×10

^{-2}Nm (B) 2π×10

^{2}Nm

(C) 4π×10

^{-2}Nm (D) 4π×10

^{2}Nm

Answer - (A).

## Homework Equations

ω=2πƒ (ƒ=frequency)

Power (P) = Γω.

P = W/t.

W = ΔK.E. = (1/2)Iω

^{2}.

## The Attempt at a Solution

The power delivered is equal to the rate of doing work which is equal to the change in rotational kinetic energy.

On calculating, I get the final answer as 10

^{-2}πN.m. Kindly help.