SECTION-6

MACHINE DESIGN MCQ

##### Q31. Two shafts, one solid and the other hollow, of the same material will have the same strength if they are having

(a) same length and same weight
(b) same length and same polar modulus
(c) same weight and same polar modulus
(d) same length, weight and polar modulus.

Ans:(b) same length and same polar modulus

##### Q32. For calculating stresses in a hollow shaft subjected to torsion, the radius taken into consideration is

(d) none of the above.

##### Q33. The largest permissible size for a dimension is known as

(a) lower limit
(b) upper limit
(c) basic size
(d) actual size.

Ans:(b) upper limit

##### Q34. The smallest permissible size for a dimension is known as

(a) lower limit
(b) upper limit
(c) basic size
(d) actual size.

Ans:(a) lower limit

##### Q35. Torsional rigidity of a shaft is equal to

(a) product of modulus of rigidity and polar moment of inertia
(b) sum of modulus of rigidity and polar moment of inertia
(c) difference of modulus of rigidity and polar moment of inertia
(d) ratio of modulus of rigidity and polar moment of inertia.

Ans:(a) product of modulus of rigidity and polar moment of inertia

##### Q36. Choose the wrong statement

(a) Ductile materials are designed on the basis of maximum shear stress theory.
(b) Brittle materials are designed on the basis of maximum normal stress theory.
(c) If the twisting moments of the two shafts are equal, they will have equal strength.
(d) A shafts is subjected to shear stresses only.

Ans:(d) A shafts is subjected to shear stresses only.

##### Q37. The torque transmitted by a rotating hollow shaft is equal to

(a) π/16  τ do3
(b) π/16  τ do3  – di3
(c) π/16  τ do3  ( 1-k4)
(d)π/16  τ do3  ( 1-k3)
where τ = Torsional shear stress, do= Outside diameter of the shaft,di = Inside diameter of the shaft, and k = di/do=Ratio of inside diameter to outsidediameter.

Ans:(c) π/16  τ do3  ( 1-k4)

##### Q38. The relation between the diameter of the solid shaft and the diameters of a hollow shaft,which is having the same material and equal in strength to the solid shaft, is given by

(a) d = do (1 – k4
(b) d = do (1 – k4)1/3
(c) d = do (1 + k2
(d) d = do (1 + k3
where d = Diameter of the solid shaft, do = Outer diameter of the hollow shaft, and
k = Ratio of inside diameter to outside diameter of a hollow shaft.

Ans:(b) d = do (1 – k4)1/3

##### Q39. A shaft is designed on the basis of

(a) strength
(b) rigidity
(c) strength and rigidity
(d) none of the above.

Ans:(c) strength and rigidity

##### Q40. Which one of the following is a wrong statement?

(a) Sudden change in cross-section should be avoided as they cause stress concentration.
(b) In brittle material, stress concentration is more serious for static loading.
(c) In cyclic loading, stress concentration is more serious in ductile materials.
(d) Stress concentration factor is the ratio of ultimate stress to working stress.

Ans:(d) Stress concentration factor is the ratio of ultimate stress to working stress.

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##### Read More Sections of Machine Design

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Machine Design MCQ – Section-1

Machine Design MCQ – Section-2

Machine Design MCQ – Section-3

Machine Design MCQ – Section-4

Machine Design MCQ – Section-5

Machine Design MCQ – Section-6

Machine Design MCQ – Section-7