Machine Design MCQs

Question 1

Cold working

Accepted Answer

Increases the fatigue strength

Answer

Decreases the fatigue strength

Answer

Has no influence on fatigue strength

Answer

Alone has no influence on fatigue strength

Question 2

A closely coiled helical spring is acted upon by an axial force. The maximum shear stress developed in the spring is $$	au $$. The half of the length of the spring if cut off and the remaining spring is acted upon by the same axial force. The maximum shear stress in the spring in new condition will be

Accepted Answer

$$	au $$

Answer

$$\frac{	au }{2}$$

Answer

$$2	au $$

Answer

$$4	au $$

Question 3

The shock resistance of steel is increased by adding

Accepted Answer

Nickel and chromium

Answer

Nickel

Answer

Chromium

Answer

Cobalt and molybdenum

Question 4

While designing a screw in a screw jack against buckling failure, the end conditions for the screw are taken as

Accepted Answer

One end fixed and the other end free

Answer

Both the ends fixed

Answer

Both the ends hinged

Answer

One end fixed and the other end hinged

Question 5

At low temperatures (say 75°C) the notched bar impact value of steel

Accepted Answer

Decreases markedly

Answer

Increases markedly

Answer

Remain same

Answer

Depends on heat treatment carried out

Question 6

Which of the following statement is correct, for two shafts connected in parallel?

Accepted Answer

Angle of twist of each shaft is the same

Answer

Torque in each shaft is the same

Answer

Shear stress in each shaft is the same

Answer

Torsional stiffness of each shaft is the same

Question 7

The value of stress concentration factor depends upon

Accepted Answer

None of these

Answer

Material and geometry of the part

Answer

Geometry of the part

Answer

Material of the part

Question 8

Which is correct statement? Stress concentration in cyclic loading is

Accepted Answer

Equally serious in both types of materials

Answer

Very serious in brittle materials and less serious in ductile materials

Answer

Very serious in ductile materials and less serious in brittle materials

Answer

Seriousness would depend on other factors

Question 9

Stress concentration factor is defined as the ratio of

Accepted Answer

Maximum stress to the nominal stress

Answer

Maximum stress to the endurance limit

Answer

Nominal stress to the endurance limit

Answer

Nominal stress to the maximum stress