mechanical engineering MCQs – Page 71

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

3501. Pour point of fuel oil is the____________________?
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A. storage temperature

B. lowest temperature at which oil will flow under set condition

C. temperature at which fuel is pumped through burners

D. none of the above

E. temperature at which oil is transported

3502. In ordetjo obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will _________________?
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A. may improve/worsen depending on size

B. improve C. worsen

C. unpredictable

D. remain unaffected

3503. Proximate analysis of fuel is determination of percentage of ____________________?
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A. carbon, hydrogen, nitrogen, sulphur, moisture

B. higher calorific value

C. fixed carbon, ash, volatile matter, moisture

D. rough analysis

E. lower calorific value

3504. Pick up the wrong statement about water tube boiler in comparison to fire tube boilers ______________________?
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A. former is used for high installed capacity

B. former generates steam at high pressure

C. former occupies less space for same power

D. rate of steam flow is more in former case

E. chances of explosion are less in former case
3505. Fire tube boilers are limited to a maximum design working pressure of ____________________?
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A. 250 kg/cm2

B. 17 kg/cm2

C. 1 kg/cm

D. 6 kg/cm

E. 100 kg/cm2

3506. The safety valve on boiler drum compared to safety valve on super heater is set at ________________?
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A. same value

B. lower value

C. lower/higher depending on steam flow

D. higher value

E. unpredicatble

3507. 02 content in atmospheric air on volume basis is___________________?
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A. 70%

B. 23%

C. 30%

D. 40%

E. 21%
3508. If three forces acting in different planes can be represented by a triangle, these will be in________________?
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A. unpredictable

B. full equilibrium

C. partial equilibrium

D. none of the above

E. non-equilibrium
3509. According to principle of moments__________________?
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A. positive and negative couples can be balanced

B. if a system of coplanar forces is in equilibrium, then their algebraic sum is zero

C. if a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero

D. none of the above

E. the algebraic sum of the moments of any two forces about any point is equal to moment of theiwesultant about the same point

3510. Friction force for dry surfaces. Friction force is________________?
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A. k up wrong statement?

B. proportional to normal load between the surfaces

C. none of the above is wrong statement

D. independent of the area of contact surfaces

E. dependent on the materials of contact surface

F. proportional to velocity of sliding
3511. In ideal machines__________________?
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A. none of the above

B. mechanical advantage is unity

C. mechanical advantage is equal to velocity ratio

D. mechanical advantage is greater than velocity ratio

E. mechanical advantage is less than velocity ratio

3512. The unit of force in S.I. units is________________?
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A. watt

B. dyne

C. newton

D. joule

E. kilogram

3513. The necessary condition for forces to be in equilibrium is that these should be_________________?
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A. coplanar

B. meet at one point ;

C. both A. and B. above

D. all be equal

E. something else

3514. The unit of work or energy in S.I. units is_______________?
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A. pascal

B. kilogram meter

C. newton

D. watt

E. joule
3515. A number of forces acting at a point will be in equilibrium if_____________________?
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A. their total sum is zero

B. two resolved parts in two directions at right angles are equal

C. sum of resolved parts in any two per-pendicular directions are both zero

D. all of them are inclined equally

E. none of the above

3516. According to principle of transmissibility of forces, the effect of a force upon a body is_________________?
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A. maximum when it acts at the center of gravity of a body

B. minimum when it acts at the C.G. of the body

C. the same at every point in its line of action

D. different at different points in its line of action

E. none of the above

3517. Which of the following is the locus of a point that moves in such a manner that its distance from a fixed point is equal to its distance from a fixed line multiplied by a constant greater than one___________________?
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A. parabola

B. hyperbola

C. circle

D. ellipse

E. none of the above

3518. The product of either force of couple with the arm of the couple is called_________________?
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A. resulting couple

B. none of the above

C. moment of the couple

D. moment of the forces

E. resultant couple

3519. The units of moment of inertia of an area are__________________?
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A. kg m2

B. kg/m4

C. kg/m2

D. m4

E. m3

3520. A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to___________________?
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A. 500

B. 50

C. 250

D. 25

E. 100

3521. D Alemberts principle is used for______________________?
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A. determining stresses in the truss

B. reducing the problem of kinetics to equivalent statics problem

C. designing safe structures

D. stability of floating bodies

E. solving kinematic problems

3522. Coefficient of friction is the_________________?
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A. angle between normal reaction and the resultant of normal reaction and the limiting friction

B. tangent of angle of repose

C. the friction force acting when the body is in motion

D. ratio of limiting friction and normal reaction

E. the friction force acting when the body is just about to move

3523. Forces are called concurrent when their lines of action meet in________________?
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A. perpendicular planes

B. one point

C. different planes

D. plane

E. two points

3524. According to Lamis theorem___________________?
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A. three forces acting at a point can be represented by a triangle, each side being proportional to force

B. none of the above

C. if three forces acting upon a particle are represented in magnitude and

D. if three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two

E. three forces acting at a point will be in equilibrium

F. ection by the sides of a triangle, taken in order, they will be in equilibrium

3525. The center of percussion of a solid cylinder of radius r resting on a horizontal plane will be_________________?
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A. r/2

B. 2r/3

C. 3r/2

D. 3r/A

E. r/A

3526. Which of the following is a vector quantity___________________?
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A. momentum

B. energy

C. angle

D. mass

E. speed

3527. The effort required to lift a load W on a screw jack with helix angle a and angle of friction <j) is equal to _________________?
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A. Wcos(a + )

B. Wsin(a + )

C. Wtan(a-)

D. Wtan(a + )

E. W (sin a + cos ).

3528. The center of gravity of a uniform lamina lies at____________________?
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A. none of the above

B. the center of heavy portion

C. the bottom surface

D. the mid point of its axis

E. all of the above

3529. A force is completely defined when we specify_______________?
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A. point of application

B. all of the above

C. direction

D. none of the above

E. magnitude

3530. Which of the following do not have identical dimensions ?
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A. Torque and work

B. Torque and energy

C. Momentum and impulse

D. Moment of a force and angular momentum

E. Kinetic energy and potential energy

3531. A semi-circular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi-cricular disc and horizontal surface is \i. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will____________________?
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A. slant up towards direction of pull

B. slant down towards direction of pull

C. none of the above

D. unpredictable

E. remain horizontal

3532. A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t2 (t 4), the acceleration of the particle will be given by the equation __________________?
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A. 6f-4

B. 3t2-lt

C. 6f-8

D. 6t2-8t

E. 3t2+2t

3533. The unit of power in S.I. units is______________?
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A. joule

B. pascal per sec

C. newton meter

D. watt

E. kilogram meter/sec

3534. Forces are called coplanar when all of them acting on body lie in __________________?
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A. one point

B. different points

C. perpendicular planes

D. different planes

E. one plane
3535. A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly_________________?
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A. 124 m

B. 96 m

C. 38 m

D. 240 m

E. 62.5 m
3536. A body of weight W on inclined plane of a being pulled up by a horizontal force P will be on the point of motion up the plane when P is equal to________________?
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A. W

B. Wtan(a +

C. W\an(a-)

D. W sin (a + $)

E. Wtana

3537. The M.I. of hollow circular section about a central axis perpendicular to section as compared to its M.I. about horizontal axis is__________________?
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A. one fourth

B. same

C. double

D. half

E. four times

3538. Tangent of angle of friction is equal to__________________?
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A. kinetic friction

B. limiting friction

C. friction force

D. coefficient of friction

E. angle of repose

3539. The C.G. of a right circular solid cone of height h lies at the following distance from the base______________?
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A. h/6

B. J/3

C. h/4

D. 3/i/5

E. h/2

3540. The co-efficient of friction depends upon_______________?
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A. A. and B. above

B. nature of surfaces

C. ail of the above.

D. shape of the surfaces

E. area of contact

3541. Coulomb friction is the friction between _________________?
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A. bodies having relative motion

B. two dry surfaces

C. electrically charged particles

D. solids and liquids

E. two lubricated surfaces

3542. Which of the following is not the unit of energy_________________?
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A. kcal

B. kg m

C. wattr

D. watt hours

E. kg m x (m/sec)2

3543. A single force and a couple acting in the same plane upon a rigid body_____________________?
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A. are equivalent

B. balance each other

C. none of the above

D. produce moment of a couple

E. cannot balance each other
3544. Center of gravity of a thin hollow cone lies on the axis at a height of ___________________?
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A. none of the above

B. one-half of the total height above base

C. one-fourth of the total height above base

D. three-eighth of the total height above the base

E. one-third of the total height above base
3545. A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve ____________________?
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A. hyperbola

B. catenary

C. parabola

D. circular arc

E. elliptical

3546. Limiting force of friction is the__________________?
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A. ratio of limiting friction and normal reaction

B. tangent of angle between normal-reaction and the resultant of normal reaction and limiting friction

C. the friction force acting when the body is just about to move

D. the friction force acting when the body is in motion

E. minimum force of friction

3547. A pair of smiths tongs is an example of the lever of__________________?
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A. zeioth order

B. second order

C. fourth order

D. third order

E. first order

3548. Which of the following is not the unit of power ?
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A. kcal/sec

B. kcal/kg sec

C. hp (horse power)

D. kW (kilowatt)

E. kg m/sec

3549. On the ladder resting on the ground and leaning against a smooth vertical wall, the force of friction will be_________________?
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A. upwards at its upper end

B. none of the above

C. perpendicular to the wall at its upper end

D. zero at its upper end

E. downwards at its upper end

3550. A sample of metal weighs 219 gms in air, 180 gms in water, 120 gms in an unknown fluid. Then which is correct statement about density of metal_________________?
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A. density of metal cant be determined

B. none of the above

C. metal is twice as dense as water

D. metal will float in water

E. metal is twice as dense as unknown fluid