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Unformatted text preview: Sec_3.3.qxd 252 9/27/08 1:27 PM Page 252 CHAPTER 3 Torsion Circular Bars and Tubes
P Problem 3.3-1 A prospector uses a hand-powered winch
(see figure) to raise a bucket of ore in his mine shaft. The axle
of the winch is a steel rod of diameter d 0.625 in. Also, the
distance from the center of the axle to the center of the lifting
rope is b 4.0 in.
If the weight of the loaded bucket is W 100 lb, what is
the maximum shear stress in the axle due to torsion? d
W Solution 3.3-1 Hand-powered winch
d 0.625 in. MAXIMUM SHEAR STRESS IN THE AXLE b 4.0 in. From Eq. (3-12): W 100 lb tmax Torque T applied to the axle:
T Wb 400 lb-in. tmax
8,340 psi ; Problem 3.3-2 When drilling a hole in a table leg, a furniture
maker uses a hand-operated drill (see figure) with a bit of
diameter d 4.0 mm.
(a) If the resisting torque supplied by the table leg is equal
to 0.3 N m, what is the maximum shear stress in the drill bit?
(b) If the shear modulus of elasticity of the steel is G 75 GPa,
what is the rate of twist of the drill bit (degrees per meter)? d ...
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- Fall '11