Machine Design MCQs

Question 1

The stiffness of a closely coiled helical spring subjected to an axial load W is equal to (where G = Modulus of rigidity and n = Number of active coils)

Accepted Answer

$$\frac{{{	ext{G}}{{	ext{d}}^4}}}{{8{{	ext{D}}^3}{	ext{n}}}}$$

Answer

$$\frac{{{	ext{G}}{{	ext{d}}^3}}}{{8{{	ext{D}}^3}{	ext{n}}}}$$

Answer

$$\frac{{{	ext{G}}{{	ext{d}}^4}}}{{4{{	ext{D}}^3}{	ext{n}}}}$$

Answer

$$\frac{{{	ext{G}}{{	ext{d}}^4}}}{{8{{	ext{D}}^2}{	ext{n}}}}$$

Question 2

For longitudinal joint in boilers, the type of joint used is

Accepted Answer

Butt joint with double cover plate

Answer

Butt joint with single cover plate

Answer

Lap joint with one ring overlapping the other

Answer

Any one of the above

Question 3

For circumferential joint in boilers, the type of joint used is

Accepted Answer

Lap joint with one ring overlapping the other

Answer

Butt joint with single cover plate

Answer

Butt joint with double cover plate

Answer

Any one of the above

Question 4

A column of length $$l$$ is fixed at both ends. The equivalent length of the column is

Accepted Answer

$$\frac{l}{2}$$

Answer

$$\frac{l}{{\sqrt 2 }}$$

Answer

$$l$$

Answer

$$2l$$

Question 5

The cracks in helical springs used in railway carriages usually start on the inner side of the coil because of the fact that

Accepted Answer

It is subjected to a higher cyclic loading than the outer side

Answer

It is subjected to a higher stress than the outer side

Answer

It is more stretched than the outer side during the manufacturing process

Answer

It has a lower curvature than the outer side

Question 6

Soderberg relation is based on __________ of the material whereas all other failure relation for dynamic loading are based on ultimate strength of the material.

Accepted Answer

Yield strength

Answer

Elastic strength

Answer

Shear strength

Answer

None of these

Question 7

When a closely coiled helical spring is subjected to a couple about its axis, the stress induced in the wire material of the spring is

Accepted Answer

Bending stress only

Answer

A combination of torsional shear stress and bending

Answer

Direct shear stress only

Answer

A combination of bending stress and direct shear stress

Question 8

Two shafts of the same length and material are joined in series. If the ratio of their diameters is 2, then the ratio of their angles of twist will be

Accepted Answer

16

Answer

2

Answer

4

Answer

8

Question 9

In oilness bearings

Accepted Answer

Do not require external supply of lubricant

Answer

The oil film pressure is generated only by the rotation of the journal

Answer

The oil film is maintained by supplying oil under pressure

Answer

Grease required to be applied after some intervals