Calculate Angle of Twist for Steel Shaft, 850 lb-in Applied

[togo]

1. Homework Statement
Compute angle of twist of one end relative to other if a torque of 850 lb-in is applied uniformly along the length. Shaft has two flats (not just the 1 pictured!) 1.25 " is measurement across flats.

Homework Equations

J = C r^4

The Attempt at a Solution

I had to hand in the page with the question on it recently :(

so, here are the governing equations, need some direction on how to tackle it:

so the value of J is easily computed (table: 0.625" / 0.875" = C of around 0.93 x 0.316 = 0.294)

angle = [(torque)(length)]/[GJ])

so since there are two J values, how is this handled? thanks

 

[rock.freak667]

I think you will need to split it as two shafts with the same torque value T. So you'd get θ₁ using J₁ and θ₂ using J₂.

The relative angle would then be θ₂-θ₁.


I could be wrong though as it's been quite long since I've done these types of things

 

[togo]

ok I'll try that

although the answer is very small and would kinda be the same even if you did it wrong. So I need to know