⚙️ 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

he tractive force in a locomotive with two cylinders is given by (where c = Fraction of reciprocating parts per cylinder, m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, and θ = Angle of inclination of crank to the line of stroke)Answer: (1 - c)m.ω2.r(cos θ - sin θ) The application of third type levers is found inAnswer: a pair of tongs The radial distance of a tooth from the pitch circle to the bottom of the tooth is calledAnswer: dedendum For unequal width of butt straps, the thickness of butt straps areAnswer: 0.75 t for wide strap on the inside and 0.625 t for narrow strap on the outside When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will beAnswer: zero In second type of levers,Answer: load is in between the fulcrum and effort The gears are termed as medium velocity gears, if their peripheral velocity isAnswer: 3 - 15 m/s Soderberg relation is based on __________ of the material whereas all other failure relation for dynamic loading are based on ultimate strength of the material.Answer: yield strength The frequency of damped vibrations with viscous damping is __________ the frequency of undamped vibrations.Answer: less than In a flange coupling, the flanges are coupled together by means ofAnswer: bolts and nuts Whitworth quick return motion mechanism consists of three turning pairs and one sliding pair.Answer: Right A transmission shaft includesAnswer: all of these A locking device in which the bottom cylindrical portion is recessed to receive the tip of the locking set screw, is calledAnswer: ring nut The rotor of a ship rotates in clockwise direction when viewed from stern and the ship takes a right turn. The effect of gyroscopic couple acting on it will be to raise the stern and lower the bow.Answer: Agree Slenderness ratio is the ratio ofAnswer: effective length of column to least radius of gyration of the column The sliding pairs, turning pairs and screw pairs form lower pairs.Answer: True A crankshaft is a __________ shaft.Answer: machine When a particle moves round the circumference of a circle of radius r with ω rad/s, then its maximum acceleration is ω2r.Answer: Right According to Indian standard specifications, 100 H6/g5 means that theAnswer: basic size is 100 mm The velocity of sliding __________ the distance of the point of contact from the pitch point.Answer: is directly proportional to A column is known as a long column if the slenderness ratio isAnswer: 100 The static frictionAnswer: all of the above A shaft has an attached disc at the centre of its length. The disc has its centre of gravity located at a distance of 2 mm from the axis of the shaft. When the shaft is allowed to vibrate in its natural bow-shaped mode, it has a frequency of vibration of 10 rad/s. When the shaft is rotated at 300 r.p.m., it will whirl with a radius ofAnswer: 2.22 mm Circumferential joint in boilers is used to get the required length of a boiler.Answer: True The swaying couple is maximum or minimum when the angle of inclination of the crank to the line of stroke (θ) is equal toAnswer: 45° and 225° The pressure angle of a cam is the angle between the direction of the follower motion and a normal to theAnswer: pitch curve The ball bearings are provided with a cageAnswer: to maintain the balls at a fixed distance apart 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 beAnswer: buttress threads A pair of friction discs is an example of rolling pair.Answer: False In order to balance the reciprocating masses,Answer: both (a) and (b)