⚙️ 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

A flanged pipe joint will be a leak-proof joint, if the circumferential pitch of the bolts is (where d = Diameter of bolt hole)Answer: between 20 √d and 30 √d The total heat rejected in a reciprocating air compressor is equal to the sum of the heat rejected during polytropic compression per kg of air and heat rejected in the intercooler per kg of air.Answer: True In a jet propulsionAnswer: the propulsive matter is caused to flow around the propelled body An open cycle gas turbine works on the same cycle as that of a closed cycle gas turbine.Answer: Yes Which of the following statement is wrong?Answer: none of the above In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in __________ of the piston.Answer: two strokes The increase in pressure in a vane blower takes place first due to compression and then due to back flow of air.Answer: Correct The maximum delivery pressure in a rotary air compressor isAnswer: 10 bar Intercooling in multi-stage compressors is doneAnswer: to minimise the work of compression The ratio of workdone per cycle to the stroke volume of the compressor is known asAnswer: mean effective pressure The ratio of workdone per cycle to the stroke volume of the compressor is known asAnswer: mean effective pressure Stress concentration is caused due toAnswer: abrupt change of cross-section he clearance volume in the compressor is kept minimum because it effects on volumetric efficiency.Answer: Correct The inlet pressure is always __________ the discharge pressure.Answer: less than The resistance to fatigue of a material is measured byAnswer: endurance limit Which of the following statement is correct?Answer: The compression ratio for the compressor is always greater than unity. The load cup of a screw jack is made separate from the head of the spindle toAnswer: prevent the rotation of load being lifted In the aircraft propellersAnswer: the propulsive matter is ejected from within the propelled body Two shafts A and B under pure torsion are of identical length and identical weight and are made of the same material. The shaft A is solid and the shaft B is hollow. We can say thatAnswer: shaft B is better than shaft A The type of rotary compressor used in gas turbines, is ofAnswer: axial flow type The volume of air delivered by the compressor is calledAnswer: compressor capacity Which of the following statement is wrong ?Answer: The V-belt drive is used with large centre distance The efficiency of a jet engine is higher atAnswer: high altitudes In a flange coupling, the thickness of flanges is taken as one-half the diameter of shaft.Answer: Agree In axial flow compressor, exit flow angle deviation from the blade angle is a function ofAnswer: blade camber and incidence angle Rotary compressors are used for deliveringAnswer: large quantities of air at low pressures The reference fuels for knock rating of spark ignition engines would includeAnswer: normal heptane and iso-octane Workdone by a two-stage reciprocating air compressor per cycle is equal to the workdone in LP. cylinder and H.P. cylinder.Answer: True The diesel engines are also known as __________ engines.Answer: compression ignition A rotary compressor is driven by anAnswer: either (a) or (b)