Mechanical Engineering Quiz # 43

A shaft is subjected to fluctuating loads for which the normal torque (T) and bending moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent twisting moment for the shaft is

2000 N-m

2050 N-m

2100 N-m

2136 N-m

When screw threads are to be used in a situation where power is being transmitted in one direction only, then the screw threads suitable for this will be

Knuckle threads

Square threads

Acme threads

Buttress threads

The root angle of a bevel gear is equal to

Pitch angle - addendum angle

Pitch angle + addendum angle

Pitch angle - dedendum angle

Pitch angle + dedendum angle

The face angle of a bevel gear is equal to

Pitch angle - addendum angle

Pitch angle + addendum angle

Pitch angle - dedendum angle

Pitch angle + dedendum angle

The longitudinal joint in boilers is used to get the required

Length of boiler

Diameter of boiler

Length and diameter of boiler

Efficiency of boiler

According to Indian standard specifications, 100 H6/g5 means that

Tolerance grade for the hole is 6 and for the shaft is 5

Tolerance grade for the shaft is 6 and for the hole is 5

Tolerance grade for the shaft is 4 to 8 and for the hole is 3 to 7

Tolerance grade for the hole is 4 to 8 and for the shaft is 3 to 7

The suitable material for belt used in flour mill is

Leather

Rubber

Canvas or cotton duck

Balata gum

When a machine member is subjected to torsion, the torsional shear stress set up in the member is

Zero at both the centroidal axis and outer surface of the member

Maximum at both the centroidal axis and outer surface of the member

Zero at the centroidal axis and maximum at the outer surface of the member

Maximum at the centroidal axis and zero at the outer surface of the member

In Vickers hardness testing, the pyramid indenter apex is

40°

122°

136°

152°

Wahl's stress factor __________ very rapidly as the spring index decreases.

Increases

Decreases

Remain same

None of these

In the levers of the first type, the mechanical advantage is ________ one.

Less than

Equal to

More than

None of these

Stress concentration is caused due to

Variation in properties of material from point to point in a member

Pitting at points or areas at which loads on a member are applied

Abrupt change of section

All of the above

According to Indian standards, a bolt thread of 6 mm size of coarse pitch and with allowance on the threads and normal tolerance grade is designated as

M6

M8

M6 - 8d

M8 - 6d

Which of the following is not a vector quantity?

Weight

Velocity

Acceleration

Force

The greatest eccentricity which a load W can have without producing tension on the cross-section of a short column of external diameter D and internal diameter d, is

4W/ (D² - d²)

(D² - d²)/32D

(D² + d²)/8D

(D² - d²)/8D

If is the shear force at a section of an I-joist, having web depth and moment of inertia about its neutral axis, the difference between the maximum and mean shear stresses in the web is,

Sd²/8I

Sd²/12I

Sd²/16I

Sd²/24I

Center of gravity of a thin hollow cone lies on the axis at a height of

One-fourth of the total height above base

One-third of the total height above base

One-half of the total height above base

Three-eighth of the total height above the base

A rectangular bar of width b and height h is being used as a cantilever. The loading is in a plane parallel to the side b. The section modulus is

Bh3

/12

Bh²/6

B²h/6

None of these

A beam is said to be of uniform strength, if

B.M. is same throughout the beam

Shear stress is same throughout the beam

Deflection is same throughout the beam

Bending stress is same at every section along its longitudinal axis

The coefficient of friction depends on

Area of contact

Shape of surfaces

Strength of surfaces

Nature of surface

A closely coiled helical spring of radius R, contains n turns and is subjected to an axial loadW. If the radius of the coil wire is r and modulus of rigidity of the coil material is C, the stress developed in the helical spring is

WR/ 3

2WR/ 3

2WR/ 2

4WR/ 2

The intensity of direct longitudinal stress in the cross-section at any point distant r from the neutral axis, is proportional to

R

1/r

R2

1/r²

The coefficient of friction depends upon

Nature of surfaces

Area of contact

Shape of the surfaces

All of the above

The force in member U2L2 of the truss shown in below figure, is

10 T tension

10 T compression

Zero

15 T compression

The angle which an inclined plane makes with the horizontal when a body placed on it is about to move down is known as angle of

Friction

Limiting friction

Repose

Kinematic friction

When loads are applied proportionately to a frame structure containing its members in one plane, the structure is called

Grid frame

Plane frame

Space frame

Truss frame

The maximum stress intensity due to a suddenly applied load is x-times the stress intensity produced by the load of the same magnitude applied gradually. The value of x is

1

2

3

1/2

The unit of power in S.I. units is

Newton meter

Watt

Joule

Kilogram meter/sec

The maximum bending moment due to a moving load on a simply supported beam, occurs

At the mid span

At the supports

Under the load

Anywhere on the beam

Which of the following is not the unit of pressure?

Kg/cm

Atm

Kg/cm²

Newton