⚙️ Mechanical Eng Solved MCQs with Answers

Practice 934 approved ⚙️ Mechanical Eng questions with verified answers from the 🛠️ Engineering Essentials subject for Pakistan exams.

934 solved MCQs

In a coupling rod of a locomotive, each of the four pairs is a __________ pair.Answer: turning If ω/ωn is very high for a body vibrating under steady state vibrations, the phase angle for all values of damping factors, will tend to approachAnswer: 180° In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only uponAnswer: total lift, total angle of lift, minimum radius of cam and cam speed When the relation between the controlling force (Fc) and radius of rotation (r) for a spring controlled governor is Fc = ar + b, then the governor will beAnswer: unstable The factor which affects the critical speed of a shaft isAnswer: all of these The partial balancing of reciprocating parts in locomotives producesAnswer: all of the above The pair is known as a higher pair, when the relative motion between the elements of a pair isAnswer: partly turning and partly sliding The sleeve or muff coupling is designed as aAnswer: hollow shaft When the connection between the two elements is such that only required kind of relative motion occurs, it is known as self-closed pair.Answer: Right A sliding bearing in which the working surfaces are completely separated from each other by lubricant is called zero film bearing.Answer: False The Whitworth quick return motion mechanism is formed in a slider crank chain when theAnswer: coupler link is fixed The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke isAnswer: 0° and 180° Screws used for power transmission should haveAnswer: high efficiency The acceleration of the particle moving with simple harmonic motion is inversely proportional to the displacement of the particle from the mean position.Answer: No The number of rivets in shear shall be equal to the number of rivets in crushing.Answer: Correct When bevel gears connect two shafts whose axes intersect at an angle greater than a right angle and one of the bevel gears has a pitch angle of 90°, then they are known asAnswer: crown bevel gears In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if ω/ωn isAnswer: equal to √2 The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω1 rad/s in the clockwise direction and the link OB turns with angular velocity ω2 rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)Answer: ( ω1 - ω2)r If ω/ωn =√ 2, where co is the frequency of excitation and ωn is the natural frequency of vibrations, then the transmissibility of vibration will theAnswer: 1 A disturbing mass m1 attached to the rotating shaft may be balanced by a single mass m2 attached in the same plane of rotation as that of m1, such that (where r1 and r2 are the radii of rotation of m1 and m2 respectively)Answer: m1r1 = m2r2 In railway axle boxes, the bearing used isAnswer: double row spherical roller bearing When the two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as aAnswer: lower pair The two elements of a pair are said to form a __________ when they permit relative motion between them.Answer: kinematic pair When the axes of the shafts, over which the gears are mounted, move relative to a fixed axis, then the train is known as reverted gear train.Answer: Wrong In under damped vibrating system, the amplitude of vibrationAnswer: decreases exponentially with time The toughness of a material __________ when it is heated.Answer: decreases The number of slots in a 25 mm castle nut isAnswer: 6 The dynamic friction is the friction experienced by a body, when the bodyAnswer: is in motion The steering of a ship meansAnswer: turning of a complete ship in a curve towards right or left, while it moves forward A screw is said to be over hauling screw, if its efficiency isAnswer: more than 50%