Can anybody help me ive been stuck for over 3 weeks

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Discussion Overview

The discussion revolves around a homework problem involving the design of a solid steel shaft versus a thin-walled hollow shaft under torque. Participants explore the calculations needed to determine the appropriate dimensions of the hollow shaft to carry the same torque while considering material properties and application constraints.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes a solid steel shaft subjected to torque and seeks to find the required diameter of a hollow shaft to carry the same torque while maintaining the same maximum allowable stress.
  • Another participant suggests that the problem can be approached by writing the stress equation in terms of radius and solving from there.
  • A third participant notes that the question resembles a take-home exam problem and emphasizes the forum's rules against providing direct solutions, urging the original poster to show their work instead.
  • The original poster clarifies that the question is part of a homework assignment for an HNC course and expresses frustration over being stuck on this and another related question involving shear force and bending moment diagrams.
  • One participant asserts that if two beams can carry the same torque, they can be stressed similarly and asks for the equation for torsional stress.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of the problem, with some believing it is straightforward while the original poster feels lost. There is a mix of perspectives on how to approach the problem and the appropriateness of providing hints or guidance.

Contextual Notes

The discussion includes unresolved aspects such as the specific equations needed for the calculations and the original poster's understanding of the concepts involved. There is also a lack of clarity regarding the rules of the forum in relation to homework help.

TWOSWORDALI
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A solid steel shaft 10 m long and 70mm diameter is subjected to a torque of 4.5 kNm.
In order to save the weight the solid shaft is to be replaced be a thin walled hollow shaft of wall thickness 10mm.
What diameter of hollow shaft is required to carry the same torque if the maximum allowable stress is the same as that experienced by the solid shaft?
If the modulus of rigdity of the steel is 80 x 109 N/m2 calculate the angle of twist for the thin walled shaft.
Considering materials/ manufacturing costs and application constraints such as weight, inertia, balance, size and reliability, describe a suitable application for each type of shaft stating why that type is more suitable than the alternative.
Ive spent 3 weeks on this darn question
 
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What part of the question are you stuck on? This seems like a 20 min. homework problem.

You can write the stress equation completely in terms of radius (given the additional information you have). From there, simply solve for it.
 
TWOSWORDALI: This sounds like a take-home final exam question, and is one of the questions on the test you posted two weeks ago in thread [thread=324821]324821[/thread]. The PF rules state we are not allowed to tell you how to approach or solve your homework problem. You must list relevant equations yourself, and show your work; and then someone might check your math.
 
no this is not a take home exam at all its a question for homework for the HNC. And I am completely LOST As far as the electrical goes I am doing alright but this is one question out of 10 that I am stuck on well its another one as well dealing with shear force an d the bending moment diagram. But this question has got me crazy. No it is not a takehome exam in the attached file is the questions that I am doing. A hint or someexplanation or somthing will be very helpful, no i do not want you to do it for me but i do seriously need some help in understanding this. Imcompletely dumbfounded with it you can check Manchester open learning and show them the question they will affirm that it is not a take home exam question
 
If two beams can both carry the same torque, then its reasonable to say that they can be stressed the same amount. Having said that.

What is the equation for torsional stress?
 

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