Torque with pulleys and bucket of water

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SUMMARY

The discussion focuses on calculating the torque exerted by a frictionless pulley system involving a bucket of water. The pulley has a radius of 0.41 m, and the bucket, with a mass of 1.53 kg, falls for 2.04 seconds, covering a distance of 2.87 m. The torque (t) is calculated using the formula t = F * R, where F is the tension in the rope, derived from the weight of the bucket and the acceleration due to gravity (9.81 m/s²). The key takeaway is that the tension in the rope, not the weight of the bucket, directly exerts the torque on the pulley.

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  • Understanding of Newton's 2nd Law of Motion
  • Basic knowledge of torque and its calculation
  • Familiarity with the concepts of tension in ropes
  • Ability to analyze motion under gravity
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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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