Interview Question Set 7

Question Set 7

What minerals are used in the manufacture of cars?

Cars are made from many various minerals. The steel body is made from the iron-rich minerals like magnetite and hematite. Door handles and badges are often coated in chromium which comes from chromite. Some of the other minerals used are aluminum, quartz, copper, magnesium, zinc, tin etc.

Which instrument measures speed in a car?

A speedometer helps measure the speed in the car.

What are the advantage and disadvantage of using LPG in a car?

Advantages:

The high octane rate enables it to blend better with air and to burn completely, generating less carbon. With less carbon buildup, spark plugs often last longer and oil changes are needed less frequently.

Since it burns in the gaseous phase, it results in less corrosion and engine wear.

In case of a spill, LPG evaporates quickly.

Disadvantages

The LPG requires servicing at approximately once a year.

Since complete combustion occurs, more heat is liberated which is not advised for a long journey as the engine will get over heated.

Installation of LPG is rather difficult.

Why gas containers are mostly in a cylindrical shape?

The ideal shape would be a sphere. The container must have the capacity to withstand the extremely high pressure of liquefied gas. A spherical shape helps in distributing these forces uniformly.

Explain why re-heater is used in gas turbine

The advantage of reheater is that it significantly increases the thrust; which is a prime reason for its use in gas turbines.

How many types of suspensions are used in automobiles?

McPherson struts
Leaf spring
Coil spring
Torsion beam
Wishbone
Air Suspension

What is DTSI? Why it is used in motor bikes?

Digital Twin Spark Ignition. This is used for a better fuel combustion in the cylinder head which helps provide better efficiency and optimum use of fuel.

What are the advantages of DTSI over normal engines?

The cylinder head has two spark plugs, instead of the usual one. When two sparks are generated at either ends of the combustion chamber, the air-fuel mixture is ignited in a way that creates two flame fronts. A higher rate of combustion is achieved leading to higher rise in pressure. The outcome of this is more torque, better fuel efficiency and lower emissions.

What is meant by gear ratio?

A gear ratio is a direct measure of ratio of the rotational speeds of two or more interlocking gears.

What is the ratio of specific heat of air?

The ratio of specific heat γ=CP/CV is a factor in adiabatic engine processes and in determining the speed of sound in gas. This ratio γ=1.66 for an ideal monoatomic gas and γ=1.4 for air, which is predominantly a diatomic gas.

What is the percentage of carbon present in pig iron?

Carbon content is generally 3.5-4.5%.