Question
Question: A man standing on a rotating table is holding two masses at arm’s length. Without moving his arms, h...
A man standing on a rotating table is holding two masses at arm’s length. Without moving his arms, he drops the two masses. His angular speed will
(A) Increase
(B) Decrease
(C) Become zero
(D) Remain constant
Solution
Here we have to use the relationship between mass and inertia to find what will happen to the angular speed of the man.
Complete step by step answer:
A physical quantity is the moment of inertia that defines how quickly a body can be rotated around a given axis. It is a mass rotational equivalent, which defines the resistance of an object to translational motion. Inertia is the property of matter which, in its state of motion, resists change. Inertia is a measure of the force at its current speed that keeps a stationary object stationary or a rotating object rotating. Inertia is the property of matter which, in its state of motion resists change.The moment of inertia for a point mass is just the mass times the square of the perpendicular distance to the axis of rotation. As any object can be constructed from a set of point masses, the point mass relationship becomes the basis for all other moments of inertia.A solid’s mass moment of inertia tests the capacity of the object to withstand changes in rotational velocity along a particular axis. The higher the mass moment of inertia, for a given torque, the greater the angular acceleration along the axis.
Given,
A man standing on a rotating table is holding two masses at arm’s length. Without moving his arms, he drops the two masses.The external force applied in the situation above is zero. So, as he lowers the masses, the moment of inertia diminishes. This corresponds to a rise in the individual’s angular velocity or speed.So, the angular velocity will increase in this case.
Hence, option A is correct.
Note: Here the main point is we have to see if any external force is present or not.
Then only the angular velocity will increase.