⚙️ 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 radial cams, the follower movesAnswer: in a direction perpendicular to the cam axis The square threads are not so strong as V-threads but they offer less frictional resistance to motion than Whitworth threads.Answer: Correct In a screw jack, the effort required to lower the load W is given byAnswer: P = W tan(φ - α) An automobile steering gear is an example ofAnswer: lower pair According to Unwin's formula, the relation between the diameter of rivet hole (d) and the thickness of plate (t) is given by (where d and t are in mm)Answer: d = 6 √t The frictional torque transmitted in a multi-collared shaft is same as that of a single collared shaft.Answer: Right In order to avoid tearing of the plate at an edge, the distance from the centre line of the rivet hole to the nearest edge of the plate should be equal to (where d = Diameter of rivet hole)Answer: 1.5 d In order to give the primary balance of the reciprocating parts of a multi-cylinder in-line engines,Answer: both (a) and (b) The value of stress concentration factor depends uponAnswer: material and geometry of the part The gear train usually employed in clocks is aAnswer: reverted gear train Which of the following material has the maximum ductility?Answer: Mild steel A mass of 1 kg is attached to the end of a spring with a stiffness of 0.7 N/mm. The critical damping coefficient of this system isAnswer: 52.92 N-s/m When a bolt is subjected to shock loading, the resilience of the bolt should be considered in order to prevent breakage at theAnswer: thread The cam follower generally used in automobile engines isAnswer: spherical faced follower In order to obtain the bolts of uniform strength, an axial hole is drilled through the head as far as the threaded portion such that the area of shank becomes equal to the root area of the thread.Answer: True An open belt drive is used whenAnswer: shafts are arranged parallel and rotate in the same directions In a four stage compressor, if the pressure at the first and third stage are 1 bar and 16 bar, then the delivery pressure at the fourth stage will beAnswer: 64 bar The compressed air may be usedAnswer: all of the above In unilateral system of tolerance, the tolerance is allowed onAnswer: one side of the nominal size A rocket works with maximum overall efficiency when air-craft velocity is __________ the jet velocity.Answer: one-half The constant factor in case of R10 series of preferred numbers isAnswer: 1.26 The volumetric efficiency for reciprocating air compressors is aboutAnswer: 70 to 90% The pipe joint mostly used for pipes carrying water at low pressures isAnswer: socket joint The maximum temperature in a gas turbine isAnswer: 700°C According to Guest's theory, the failure occurs at a point in a member when the maximum shear stress in a bi-axial stress system reaches the shear stress at elastic limit in simple tension test.Answer: True The rotary compressors are suitable for large discharge of air at low pressure.Answer: True Surface endurance limit of gear material is dependent upon itsAnswer: brinell hardness number In a hydrodynamic lubricated bearingAnswer: there is a thick film of lubricant between the journal and the bearing Which of the following statement is correct for gears?Answer: All of the above The stagnation pressure rise in a centrifugal compressor takes placeAnswer: in the diffuser and impeller