A solid disk of radius 23.4cm and mass 1.45kg....

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Homework Help Overview

The problem involves a solid disk and a solid cylinder, focusing on their rotational dynamics when the cylinder is dropped into the center of the spinning disk. The subject area includes concepts of rotational motion and energy in physics.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to determine the final angular velocity and the change in mechanical energy of the system. Some participants request to see the original poster's work to better understand their reasoning. There are discussions about the appropriate equations to use for calculating mechanical energy.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the original poster's calculations and the equations involved. There is an emphasis on understanding the context of the equations rather than just presenting them.

Contextual Notes

Participants are navigating the complexities of rotational dynamics, including the interaction between the spinning disk and the stationary cylinder. There may be constraints related to the homework guidelines that influence the discussion.

HappyFlower
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Homework Statement


A solid disk of radius 23.4 cm and mass 1.45 kg is spinning at 43.1 radians per second. A solid cylinder of radius 12.1 cm and mass 3.33 kg is not spinning. The cylinder is dropped into the center of the spinning disk. After a short time friction has caused both objects to engage and turn in the same direction and rate.
a) Determine final rotational direction and angular velocity of the system?
b) Determine the change in mechanical energy of the system?

Homework Equations

The Attempt at a Solution


i found a) 26.7 rad/s
I am having trouble finding the mechanical energy I don't know which equation I should use. I tried using
K=Iwf^2-Iwi^2
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Last edited:
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Please show your work.
 
Orodruin said:
Please show your work.
I fixed it.
 
HappyFlower said:
I fixed it.
Rather than just writing down equations, you should explain what those equations are for. For instance:

You have a cylinder sitting on a disk such that both are rotating at the same angular velocity. You have determined that angular velocity. What is the total rotational kinetic energy of the assembly?
 

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