What is the torque if the rope is attached

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Homework Help Overview

The problem involves calculating the torque exerted on a large stone obelisk being tilted into place using a rope and pulley system. The obelisk is 8 meters tall, and the force applied by the donkeys is constant at 4500N. The discussion focuses on different scenarios based on the attachment points of the rope.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the torque calculations for different attachment points of the rope, questioning the pivot point for torque calculation and the correctness of the initial attempts. There is also a consideration of rounding in calculations.

Discussion Status

Some participants agree on the correctness of the calculations for the first two scenarios, while there is a debate regarding the third scenario. Guidance is offered regarding the interpretation of the attachment point and its impact on the torque calculation.

Contextual Notes

The original problem does not specify the pivot point for torque calculations, leading to some uncertainty in the discussion. There are also concerns about rounding in the calculations presented.

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Homework Statement


a large stone obelisk that is 8meters tall is laid down flat in the center of a Roman piazza and is going to be tilted into place by a rope and pulley system tied to a team of donkeys. If the team of donkeys always pulls with a constant force of 4500N, what is the torque if:
a) the rope is attached to the middle of the obelisk
b) the rope is attached to the end of the obelisk at a 45 degree angle?
c) the rope is attached perpendicularly to the end of the obelisk?

Homework Equations


t = F * I

The Attempt at a Solution


a) 4m * 4500 = 18,000N*m
b) (8m)(cos45)(4500N) = 25455N*m
c) is it zero?
 
Last edited:
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hmm. The question doesn't say what point the torque is meant to be calculated around. But I think you have chosen the correct point (the pivot point), this seems the most obvious choice.

I think you've got questions a) and b) right (But be careful with the rounding in part b, it looks like you have rounded down when it should have been rounded up). For question c, think of how the rope was attached in question a.
 
a and b are right. c is 8*4500=36,000
 
That sounds right to me. (I'm guessing you have had your work marked already?) Do you get why the answer to c is what it is?
 

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