### 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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