MECHANICAL ENGINEERING MCQ SECTION 10

MECHANICAL ENGINEERING MCQ SECTION 10

91. Brittle fracture is more dangerous than ductile fracture because

(A) No warning signs

(B) Crack propagates at very high speeds

(C) No need for extra stress during crack propagation

(D) All of the mentioned above

Answer: - All of the mentioned above

92. A transmission shaft subjected to bending and torsional moments should be designed on the basis of

(A) Maximum principal stress theory

(B) Maximum shear stress theory

(C) Permissible bearing pressure

(D) None of the mentioned above

Answer: - Maximum shear stress theory

93. In a petrol engine, the tendency for detonation increases with

(A) Retarded spark timing

(B) Running the engine at high speed

(C) Supercharging

(D) Increasing the cooling rate

Answer: - Supercharging

94. Ammonia used as refrigerant is non-corrosive to

(A) iron and steel

(B) copper and copper alloys

(C) Both (A) and (B)

(D) Neither (A) nor (B)

Answer: - iron and steel

95. The number of points of contra flexure in a simple supported beam carrying uniformly distributed load, is

(A) One

(B) Two

(C) Zero

(D) None of these

Answer: - Zero

96. For applications involving high stresses in one direction only the following type of thread would be best suited

(A) ISO metric thread

(B) Acme thread

(C) Square thread

(D) Buttress thread

Answer: - Buttress thread

97. Ball bearing type screws are found in following application

(A) Screw Jack

(B) Aeroplane engines

(C) Crane

(D) Steering Mechanism

Answer: - Steering Mechanism

98. The fatigue life of a part can be improved by

(A) Polishing

(B) Coating

(C) Shot peening

(D) Heat treating

Answer: - Shot peening

Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals and composites. It entails impacting a surface with shot with force sufficient to create plastic deformation.

(Text source Wikipedia)

99. A fuel of cetane number 40 has the same ignition quality as a mixture of

(A) 40% cetane and 60% alpha methyl naphthalene

(B) 40% alpha methyl naphthalene and 60% cetane

(C) 40% petrol and 60% diesel

(D) 40% diesel and 60% petrol

Answer: - 40% cetane and 60% alpha methyl naphthalene

100. Thermoplastic materials are those materials which

(A) are formed into shape under heat and pressure and results in a

permanently hard product

(B) do not become hard with the application of heat and pressure and no chemical changes occurs

(C) are flexible and can withstand considerable wear under suitable

conditions

(D) are used as a friction lining for clutches and brakes

Answer: - do not become hard with the application of heat and pressure and no chemical changes occurs