Review time!
is an equation that tells you that the is equal to times
Equations of motion are
Where v=, a=, t=, v0=. The 0 in v0 stand for d=
p=mv tells you that is equal to the times
has units that are because work is a
Tells you that the of an object is half its times its
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.
There will be a lot of talk of what is linear or translational motion and what is rotational motion
a bike frame moving down the street
the bike wheel rolling down the street
a kid on a merry go round
a kid flying off a merry go round
a rock inside a slingshot
a rock released from a slingshot
translational
rotational
both
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?