Use conservation of energy to determine the angular speed of a spool

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Homework Help Overview

The problem involves using conservation of energy to determine the angular speed of a spool after a bucket has fallen a certain distance. The subject area includes concepts from mechanics, specifically energy conservation, rotational dynamics, and kinematics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between potential energy and the kinetic energies involved as the bucket falls. There are attempts to formulate equations that relate these energies, including questions about the variables involved, such as the velocity in translational kinetic energy.

Discussion Status

The discussion is ongoing, with participants exploring the relationships between potential energy and kinetic energies. Some guidance has been offered regarding the equations to use, but there are still uncertainties about specific variables and the implications of missing information, such as the mass of the spool.

Contextual Notes

There is a noted constraint regarding the mass of the spool not being provided, which raises questions about how to proceed with the calculations for rotational kinetic energy.

mizzy
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Homework Statement



Use conservation of energy to determine the angular speed of a spool after the bucket(3.0kg) has fallen 4.00m, starting from rest.

Homework Equations


KE = 1/2mv^2

KEr = 1/2 * I * omega^2

PE - mgh


The Attempt at a Solution



i don't know how to start. I know that I'm suppose to add the change in kinetic translational and kinetic rotational and potential energies.

Can someone guide me on this please?
 
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As the bucket falls 4m, what is the energy associated here and what is its quantity?

This energy is converted into translational and rotational kinetic energy, so can you form an equation relating the three equations?
 
potential energy = -mgh

change in KEt + change in KEr + change in PE

is that right? but what is v in KEt?
 
mizzy said:
potential energy = -mgh

change in KEt + change in KEr + change in PE

is that right? but what is v in KEt?

So you will have mgh=KEt+KEr

you also should know that v=rω.
 
rock.freak667 said:
So you will have mgh=KEt+KEr

you also should know that v=rω.

k. mass of the spool is not given so how can we solve the KEr??
 
The m's cancel in the equation.
 

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