Torque with pulleys and bucket of water

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Homework Help Overview

The discussion revolves around a physics problem involving torque, pulleys, and a bucket of water. The scenario includes a frictionless pulley with an unknown mass and a bucket that falls a certain distance over a specified time, raising questions about the forces and torques involved in the system.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to determine the torque exerted on the pulley and the tension in the rope. There is some confusion regarding the forces at play and the correct application of Newton's laws.

Discussion Status

Some participants are clarifying the question and the relevant forces, while others are exploring the relationship between the tension in the rope and the torque on the pulley. Hints have been provided to analyze the forces acting on the bucket and to consider the acceleration involved.

Contextual Notes

There is an emphasis on neglecting the mass of the cord, and the participants are working with specific values for mass, radius, and distance fallen. The setup includes assumptions about the pulley being frictionless.

mikefitz
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Imagine a frictionless pulley (a solid cylinder) of unknown mass M and radius r = 0.41 m is used to draw water from a well. A bucket of mass m = 1.53 kg is attached to a cord wrapped around the cylinder. A bucket starts from rest at the top of the well and falls for t = 2.04 s before hitting the water h = 2.87 m below the top of the well. Neglect the mass of the cord.

t = F*R
t=(1.53*9.81) * .41

t = 6.15 Nm??
 
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What's the question? (Find the unknown mass of the pulley?)

Hint: What directly exerts the torque on the cylinder is the tension in the rope, not the weight of the bucket.
 
sorry, the question is asking what the torque is; i can't seem to figure it out for some reason?
 
Find the tension in the rope.

Hints: Analyze the forces acting on the bucket. Apply Newton's 2nd law. (What's the acceleration of the bucket?)
 

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