How does mass affect angular acceleration?

1 Answer
Jan 20, 2016

Angular acceleration is inversely proportional to mass.

Explanation:

For rotational motion, adapting Newton's second law to describe the relation between torque and angular acceleration:

tau = I.alpha ,

where tau is the total torque exerted on the body, and I is the mass moment of inertia of the body.
This can also be written as
alpha=tau/I...................(1)

We know that Moment of inertia Iof regular body is given as
I=mr^2 where m is its mass and r, is the radius of the circular path of rotation.

implies I prop m

Substituting in equation (1) above we obtain.

alpha prop tau/m
or alpha prop m^-1

*Hope this helps.

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For sake of completeness.

Angular acceleration is the rate of change of angular velocity and is denoted as alpha.

This can be defined either as:
alpha -= (d omega)/dt = (d^2theta)/dt^2 , or as

alpha = a_T/r ,

where omega is the angular velocity, a_T is the linear tangential acceleration, and r, is the radius of the circular path in which a point rotates or distance of the rotating point from origin of coordinate system which defines theta and omega.