This post will be useful for the students who are preparing for an interview to get placed in a mechanical-oriented Company. These are the following 10 questions which are frequently asked in an interview of a mechanical Engineering company.
1. WHAT IS THE DIFFERENCE BETWEEN MANUFACTURING AND PRODUCTION?
MANUFACTURING: The term manufacturing is the process of converting the raw materials into the finished products.
It uses different manufacturing process and also machines and labors.
PRODUCTION: The term production is the process of converting the input to output. Production is also the process of converting the raw materials into finished products but economic considerations are taken into account.
Economic considerations are the financial status(profit,loss) of a company.In manufacturing these economic status are not considered.
2. WHAT IS THE DIFFERENCE BETWEEN PETROL ENGINE AND DIESEL ENGINE?
The main difference between petrol engine and diesel engine is that in petrol engine spark plug is used for the process of ignition whereas in diesel engine spark plug is not used instead they use compressed air for the process of ignition.
Thus petrol engines are called spark ignition(SI) engines and diesel engines are called compression ignition engines(CI).
The petrol engines use otto cycle whereas the diesel engine uses diesel cycle.
3. WHAT IS THE DIFFERENCE BETWEEN 4 STOKE ENGINE AND 2 STROKE ENGINE?
In four stroke engine,the thermodynamic cycle is completed in four strokes of the piston or two revolutions of the crankshaft.In two stroke engine,the thermodynamic cycle is completed in two stroke of the piston or one revolution of the crankshaft.
Four stroke engines have valves and uses valve actuating mechanism for opening and closing of the inlet and exhaust valves.
The two stroke engine uses ports.Transfer ports are used to push the exhaust gases out of the cylinder.
4. WHAT ARE THE MODES OF HEAT TRANSFER?
There are three modes of heat transfer.They are
- Conduction.
- Convection.
- Radiation.
Conduction: The term conduction is defines as the process of transferring the heat from a hotter region to colder region without involving any actual movement of molecule. Example: frying the vegetables in the pan.
Convection: The term convection is the process of transferring heat into the liquid and gases.Here the actual movement of molecules occur due to phase change.
Example:Heating water in a container.
Radiation: The heat transfer which occurs due to the emission of electromagnetic waves are called radiation. In radiation process there is no medium involved.
Example: In microwave heat is transferred to the substance without any medium involved.
5. WHAT IS THE DIFFERENCE BETWEEN FLUID AND LIQUID?
The term fluid is applicable to substance that can flow.The fluids can be further divided into two types.They are
- Compressible fluids
- In-compressible fluids
Gases are compressible fluids whereas liquids are in in-compressible fluids.Thus liquids comes under one of the category of fluids.
“Hence all liquids are fluids but not all fluids are liquids”
6. DEFINE STRESS AND STRAIN
Stress is the Resistance to Deformation offered by the material per unit area.
Stress=Load/Area.
It’s unit is N/m2
The strain is defined as the ratio of change in length to the original length
Strain =change in length/original length
It has no unit.
7. WHAT IS THE DIFFERENCE BETWEEN MASS AND WEIGHT?
The term mass is the amount of matter contained it. Here gravity is not taken in to consideration.
The unit of mass is kilogram(kg).
The term weight is the product of mass and gravity. Here gravity is considered. The unit of weight is represented in Newton(N).
Weight = Mass * gravity = Kg * m/s2 = Newton.
8. WHAT IS ELASTICITY AND PLASTICITY?
Elasticity of a material is defined as the ability to return to its original position after being stretched or compressed.
Plasticity of a material is defined as the the ability of the material to change its shape and also molded when an external force is applied to it
9. WHAT IS YOUNG’S MODULUS AND MODULUS OF RIGIDITY?
The Young’s modulus is also called as modulus of elasticity.It is the mechanical property of a material to withstand compression or elongation with respect to its length. The Young’s modulus is also defined as the ratio of its stress to strain Young’s modulus = stress / strain. The modulus of rigidity is defined as the ratio of its shear stress to the Shear Strain within the elastic limit.
Modulus of rigidity =shear stress/shearstrain
10. WHAT IS THE DIFFERENCE BETWEEN CENTRIFUGAL AND CENTRIPETAL FORCE?
The force which acts on a body moving in a circular motion with fixed axis such that the body is directed towards the centre of the axis is called centripetalforce The force which acts on a body moving in a circular motion with a fixed Axis such that the body is directed away from the centre of the axis is called centrifugalforce