The Physics Of Ice Skating (Part 3)

In today's blog post, I will be going through several phenomenons that occur during ice skating!

Angular and Linear Momentum

Angular momentum characterizes an object's resistance to change in rotation. The basic idea is the same as with linear momentum, moving objects like to keep moving, and to change their motion we have to apply a force. If no force is present then the momentum does not change. In the case of rotation the force is called torque, applying torque to speed up rotation and decreasing torque to attain a slow rotation. When torque is applied the angular momentum increases. It slows down as time passes due to frictional torque, this is similar to friction in linear momentum. As in the case of ice skating this frictional torque is very little, because of the ice and the thin blades of the skate shoes, the skater is nearly friction less when in contact with the  ice.

Rotational Inertia

For  straight line motion, inertia is referred to as mass. For rotational motion, it's a little more. It's harder to make a given mass rotate around an axis if it is further from the axis than one that it's close to. 

E.G Coin Spinning and Stopping a Turntable Disc

Spinning a smaller coin will result in more spins, which means a faster speed, due to the fast speed it takes longer to fall. However spinning a larger coin will result in less spins and because of the slow momentum it has it loses its rotation around the axis quicker and falls flat much sooner than a smaller coin. Also the bigger coin needs more energy to produce 1 spin as compared to the smaller coin so the bigger coin loses energy at a much faster rate.

Stopping a disc that is being played on a turntable, you will find that it is much easier to stop a disc rotating by placing your finger at the border of the circle, but as you get closer towards the center of the disc it is much harder to stop the rotation, this is because you are moving closer to the rotational axis.

Summary

-Rotational inertia characterizes the resistance to change in rotation

-Torque is the type of force which makes something rotate

-Angular momentum is conserved if there is no net torque on an object. A change in rotational inertia is compensated by a change in rotation speed.

Thanks for reading my final blog post!