you are spinning on a playground merry-go-round. you are hanging on for dear life as you spin, body entirely off the disk of safety. is your body
Explain why this is what happens on a merry-go-round
What do you think angular acceleration means?
We now have several equations to consider for angular motion. Match the angular version to the translational version
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Consider the movement of the kid on the merry go round. If the kid suddenly lets go, describe his motion
the arc length of the path of the scared merry-go-round kid near the center is different for the kid sitting on the edge of the merry go round.
Because the two kids go around the whole circle in the same time, but one travels a longer arclength, the kid on the edge has a higher angular velocity than the kid near the center.
Oh hey! this is what Ben mentioned in class. I had actually totally forgotten that this is used in angular motion, because I am completely comfortable making myself the center of the universe and discussing clockwise and counterclockwise. It's a pretty good idea to use the right hand rule here, though, since we will be seeing that again in the emag section, and, to be fair, it is doing pretty much the exact same thing in that scenario.
Anyway - give me an example of what he means by clockwise and counter-clockwise are observer dependent.
Mass has a rotational equivalent too - it is called moment of inertia. Remember that mass is just the measure of inertia, think of that as measure of TRANSLATIONAL inertia. if the translational inertia can be described by the amount of stuff something is made of, what do are you guessing moment of inertia will involve?
Axis of rotation means the point around which everything spins. What is the axis of rotation of a door?
That's right, to find the rotational inertia of a system you have to find the moment of inertia of every tiny piece of your object. Making this easier, lets assume with have a tiny mass of 1kg is rotating around a stick. the equation for that situation would be
What kind of relationship is this?
what do you think
what is the center of mass?