Question #a1106

1 Answer
Nov 28, 2015

Power in rotational motion = Torque . angular velocity ( w )
Power = Scalar

Explanation:

Key point : Try to develop the study of rotational motion parallel to the study of translational motion .
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In Translatory motion
If we apply a force ,say F, on an object , and the force causes a net displacement of the object , then we say work is done .
In that case we have , W= F.s .

Now , P = W / T , here work done is that of translational motion.

In rotational motion
When a torque / moment of force ( analogue of force in rotational motion) causes a body to rotate by an angular displacement theta , then we have W= T. theta

Similar to translational , P = W/T ,here work done is that of rotational motion .

Now ,
P=dW/dt=Τ(dθ/dt)=Τω ( d theta is used here as a the angular displacement theta is very small)

In vector notation
P=Τ.ω ( since, theta / t = omega )