Machine Design 1 Elements 3

Question 1

Hooke’s law holds good up to

Answer 1

elastic limit

Question 1

The ratio of the ultimate stress or yield stress of a material to the design stress is known as

Answer 1

factor of safety

Question 2

The modulus of rigidity for mild steel is approximately equal to

Answer 2

80 GPa

Question 3

The ratio of linear stress to linear strain is called

Answer 3

Modulus of elasticity

Question 4

The Young’s modulus for mild steel is approximately equal to

Answer 4

210 GPa

Question 5

When a hole of diameter ‘d’ is punched in a metal of thickness `t’, then the force required to punch a hole is equal to

Answer 5

πdtSu

Question 6

A localised compressive stress at the area of contact between two members is known as

Answer 6

bearing stress

Question 7

The stress in the bar when load is applied suddenly is …………. as compared to the stress induced due to gradually applied load

Answer 7

double

Question 8

The yield strength for shear is reduced by as much as ………. of the yield strength

Answer 8

40%

Question 9

It is the property of a material that is usually measured in terms of percentage elongation and percentage reduction in area.

Answer 9

none of the above

Question 10

It is the amount by which the actual size of the shaft is less than the actual size of the mating hole in an assembly.

Answer 10

clearance

Question 11

In torsion, the maximum stress happens at

Answer 11

the outermost fiber

Question 12

Guest’s theory is used for

Answer 12

ductile materials

Question 13

A stress which varies from a minimum value to a maximum value of the same nature (i.e. tensile or compressive) is called

Answer 13

varying stress

Question 14

When a material is subjected to fatigue loading, the ratio of its ultimate tensile strength to its endurance limit is

Answer 14

0.50

Question 15

Failure of a material is called fatigue when it fails

Answer 15

below the yield point

Question 16

The resistance to fatigue of a material is measured by

Answer 16

endurance limit

Question 17

It is an external load whose line of action is parallel but does not coincide with the centroidal axis of a machine component.

Answer 17

eccentric load

Question 18

A square-threaded jack has a lead angle of λ. The jack will be self-locking when the coefficient of friction (f) is

Answer 18

f > tan λ

Question 19

When helical compression spring is cut into halves, the stiffness of the resulting spring will be

Answer 19

double

Question 20

To ensure self -locking in a screw jack, it is essential that the helix angle is

Answer 20

smaller than friction angle

Question 21

A screw is said to be self -locking screw, if its efficiency is

Answer 21

less than 50%

Question 22

The ratio of the load on a spring to its corresponding axial deflection

Answer 22

spring scale

Question 23

Which of the following thread is not used for power transmission in either direction?

Answer 23

Buttress thread

Question 24

Wahl’s factor is related to the spring index, such that it _______, as the spring index decreases

Answer 24

increases very rapidly

Question 25

Two helical coil springs with stiffness k1 and k2 respectively are connected in series. The stiffness of an equivalent spring is given by

Answer 25

(k1k2)/( k1+k2)

Question 26

When a helical compression spring is subjected to an axial compressive load, the stress induced in the wire is

Answer 26

none of the above

Question 27

When helical compression spring is cut into quarters, the stiffness of the resulting spring will be

Answer 27

quadruple

Question 28

This type of end connection for compression helical spring can best minimize if not eliminate the possibility of eccentric application of load.

Answer 28

squared and ground ends

Question 29

This type of screw is primarily used to prevent relative motion between two parts

Answer 29

set screw

Question 30

This form of screw thread is a modification of square thread and has rounded top and bottom

Answer 30

knuckle thread

Question 31

Two shafts A and B are made of the same material. The diameter of the shaft A is twice as that of shaft B. The power transmitted by the shaft A will be ……….. of shaft B

Answer 31

eight times

Question 32

Which of the following loading is considered for the design of axles?

Answer 32

Bending Moment only

Question 33

The strength of a shaft with a keyway is almost reduced by as much as

Answer 33

25%

Question 34

A basic shaft is one whose

Answer 34

upper deviation is zero

Question 35

In designing a connecting rod, it is considered like ………….. for buckling about X-axis.

Answer 35

both ends hinged

Question 36

When a shaft is subjected to a bending moment M and a twisting moment T, then the equivalent twisting moment is equal to

Answer 36

(M^2 + T^2)^1/2

Question 37

A type of end fixity where the end of the column is guided so that it cannot sway from side to side, but offers no resistance to rotation of the end.

Answer 37

pinned-end

Question 38

A transmission shaft subjected to bending loads must be designed on the basis of

Answer 38

maximum normal stress theory

Question 39

The connecting rod of rectangular cross-section will be equally strong in buckling about X-axis and Y-axis, if

Answer 39

Ixx=4Iyy