top 25 mechanical engineering interview questions & answers

1. Explain the reason that why big tyres are used in rear of vehicles.

1. Large tyres provide larger surface area touching the ground, thus providing the more pulling power. Basically tractors have larger rear tyres because tractors don’t have to operate at higher speeds, thus getting the same ground speed with larger tyres. Moreover gear ratios don’t have to be as high as b/c of the tyres.

2. Explain the reason that why the tyres are always black in colour. Is this phenomena related to the heat conduction?

Tyres colour is black due to the proportion of carbon mixed in it during the vulcanization of the rubber, to make the tyre shear resistant. Without vulcanization tyres won't be able to bear the friction heat and stress of the road. Thus carbon is responsible for giving tyres the prominent black colour. Adding of carbon prevents tyres from rapidly deteriorating because when ozone combines with the ultraviolet light from the sun. It attacks the polymer of the tyre.

interview Q & A (Part-5)

1. What is the difference between scavenging and supercharging?

1.Scavenging is a process of flushing out burnt gases from engine cylinder by introducing fresh air into the cylinder before exhaust stroke ends. Supercharging is the process of supplying the higher mass of air by compressing the atmospheric air.

2. Why entropy change for a reversible adiabatic process is zero?

2. Because there is no heat transfer in this process.

3.What are two essential conditions of perfect gas?

3.It satisfies the equation of state and its specific heats are constant.

4.Enthalpy and entropy are functions of one single parameter. Which is that?

4.Temperature.

Interview Q & A (Part-4)

1.What is fluid ? What is fluid mechanics ?

1.A fluid is a substance which always responses to shear stress and doesn’t have any definite shape. It may or may not have any definite volume.

2.How to determine the characteristics of fluid flow ?

2.By the values of Reynolds Number.

Interview Q & A (part-3)

1. WHAT IS 2-STROKE IC ENGINE?

1.AN 2-STROKE engine is designed by DUGLAD CLERK in 1880, the suction,compression,expansion and exhaust takes place during 2-stroke of piston.Their is 1 stroke after every revolution of the crank shift.

2. WHAT IS 4-STROKE ENGINE?

2.A 4-stroke engine is an internal combustion engine in which the piston completes four separate strokes— intake, compression, power, and exhaust— during two separate revolutions of the engine’s crankshaft, and one single thermodynamic cycle.It uses natural gas,manufactured gas.

Interview Q & A (Part-2)

1. Explain the second law of thermodynamics.

1.The entropy of the universe increases over time and moves towards a maximum value.

2. What is ferrite?

2.Magnetic iron rock

3. What is the alloy of tin and lead?

3.A tin and lead alloy is commonly called solder. Usually solder is a wire with a rosin core used for soldering. The rosin core acts as a flux.

4. What is gear ratio?

4.It is the ratio of the number of revolutions of the pinion gear to one revolution of the idler gear.

Interview Q & A (Part-1)

1. Materials having lowest cutting speed is a. Cast iron b. Bronze c. Aluminum d. High carbon steel Answer: d. High carbon steel 2. When material is ductile and cutting speed is high, then a. Continuous chips are formed b. Continuous chips with built up edges are formed c. Discontinues chips are formed d. None of these Answer: a. Continuous chips are formed