ap physics c: mech study guides

5.3 Rotational Dynamics and Energy ๐Ÿž

#rotation

#rotational-dynamics

#rotational-energy

#rigid-body-diagram

โฑ๏ธย ย 1 min read

written by

Daniella Garcia-Loos

daniella garcia-loos

November 5, 2020


5.3: Rotational Dynamics and Energy ๐Ÿž

Rotational Dynamics

Rotational Dynamic Equilibrium: This is essentially the rotational analog for Newton's Second Law in which the sum of the net torques is equal to the rotational inertia times the angular acceleration(which should be constant if force is not variable).

ฮฃTnet=Iษ‘

This means that the further away from the axis the greater the torque is! In addition to this force analog, we also have an analog for one of the most important parts of a problem in physics: force diagrams/free body diagrams. This analog is most commonly referred to as a rigid body diagram. It is very similar to an FBD, except you can see where the force is being applied to the diagram! They usually look something like:

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Taken from OpenStax

A large portion of the time you will have to use force diagrams and equations in conjunction with torque!

Rotational Energy

As with almost everything else that is translational, there is a form of rotational energy! This does not mean that there isn't any other type of energy occurring though! Most of the time there will be a combination of translational and rotational kinetic energy.

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Practice Questions:

1)

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Taken from College Board

Answer:

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2)

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-r6e1uGgkim3y.png?alt=media&token=05e2574f-07d2-4622-9bc6-b1f20572893d

Answer:

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-V17uSIrPFds0.png?alt=media&token=ae85a4f0-fb1a-4977-ab09-a117abbb0fec

3)

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-fsVIFY7FuuiR.png?alt=media&token=0d451135-e490-4744-9c83-51538bad202c

Answer:

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-i4UVDMhQmQTN.png?alt=media&token=aad3d57e-e1cd-40d1-8e1b-2fc3c93f463d

4)

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Answer:

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-8LLrml0UCFBg.png?alt=media&token=e591ffe8-9fa5-4390-b51d-39ca4a899597

5)

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Answer:

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ydXxZ7tBGUWh.png?alt=media&token=ed97f966-9967-49a1-8d35-7bdf9400617b

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