Strength of Materials (Torsion of Shafts)

Q.1.     A propeller shaft in a ship is 350 mm in diameter. the allowable working stress in shear is 50 MPa and the allowable angle of twist is 1 degree in 15 diameters of length. If G = 85 GNm-2, then the shaft can transmit a maximum torque of
(a)        350 kNm
(b)        378 kNm
(c)        416 kNm
(d)        545 kNm

Q.2.     In the above problem if a 175 mm axial hole is bored through the length of shaft and if other conditions remain same then torsional load carrying capacity of the shaft will be reduced by
(a)        1%
(b)        3%
(c)        6%
(d)        9%

Q.3.     In the above problem, by what percentage is the weight of the shaft reduced?
(a)        25%
(b)        50%
(c)        75%
(d)        53.6%

Q.4.     If the driving torque is applied at one end and the resting torque at the other end then the shafts are said to be joined in
(a)        series
(b)        parallel
(c)        a combination of series and parallel
(d)        none of these

Q.5.     If two shafts are joined in series then
(a)        resulting shaft is called compound(composite) shaft
(b)        both shafts carry the same torque(T)
(c)        total angle of twist at the fixed or resisting end(q) is the sum of separate angles of twist of the two shafts
(d)        all of the above

Q.6.     The shafts are said to be joined in parallel if
(a)        torque(T) is applied at the junction of the two shafts
(b)        resisting torques T1 and T2 are applied at their ends
(c)        both (a) and (b)
(d)        neither (a) nor (b)

Q.7.     If two shafts are connected in parallel then
(a)        resulting shaft is called composite(or compound) shaft
(b)        angle of twist in each shaft will be equal
(c)        both (a) and (b)
(d)        neither (a) nor (b)

Q.8.     A compound shaft is composed of a 500 mm length of solid copper 100 mm in diameter, joined to a 1 m length of solid steel 125 mm in diameter. A torque of 15 kNm is applied to each end of the shaft. The maximum shear stress in copper will be(G for copper = 40 GNm-2 and G for steel is 85 GNm-2)
(a)        76 MPa
(b)        39 MPa
(c)        47 MPa
(d)        88MPa

Q.9.     In the above problem, maximum shearing stress in steel will be
(a)        76 MPa
(b)        39 MPa
(c)        47 MPa
(d)        88 MPa

Q.10.   In the above problem, total angle of twist of the entire shaft will be
(a)        0.016 rad
(b)        0.026 rad
(c)        0.046 rad
(d)        0.5 rad

Answers
1. c      2. c      3. a      4. a      5. d      6. c      7. c      8. a      9. b      10. b

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