Question

Answer the following questions about moment of inertia:

1) What is the physical significance of the y-intercept (I0)? (MOMENT OF INERTIA (I) VS RADIUS (r^2) graph)

2) How might the friction influence the calculations of moment of inertia?

3) When a figure skater does a spin and then pulls in his/her arms, the spin rate increases. Why is this?

Answer 1

1) Moment of inertia, I = mr²

Now compare above equation with y = mx + c and draw a graph

When we draw graph by taking I on Y axis and r² on X axis, we will get a straight line with no intercept.

2) Moment of inertia show the resisting tendency of a body for rotation. In calculation of moment of inertia, friction may help a body to change it's state of rest and hence may increase it's value.

3) When a figure skater draws his/her arms inward, he/she reduces the distance between the axis of rotation and some of his/her mass, reducing his/her moment of inertia. Since angular momentum is conserved, his/her rotational velocity or spin rate increases to conserve angular momentum.