Basic concepts of Mechanical Engineering

There are lots of things to learn in Engineering and Mechanical is one the most important part of it. Here I have mentioned some of the most common and useful concepts of Mechanical Engineering. Here is the list
1. Prime movers and its types
2. Force and mass
3. Pressure
Part 2 (4. Work, 5. Power, 6. Energy, 7. Heat, 8. Temperature)

1. Prime Movers and its types

For generations, the human society has been using energy in various forms for carrying out all of its activities. Man is using energy practically for doing almost everything, i.e. to cook food, to run household appliances, to do work, to run machines etc.
Most of the energy that we have been using now mainly comes from natural sources like coal, petroleum, natural gas etc.
Prime mover is a device which uses natural sources to convert their energy into mechanical energy or useful work(shaft power).

types of prime movers

the prime mover can be classified according to the sources of energy utilized.

2. Force and Mass

i) Force:
 Force is the product of mass and acceleration of the body to which it is applied.
As per Newton's second law of motion

            force ∝ acceleration 

F ∝ a 

∴ F = m×a 

where m is(constant) mass of a body in kg.

In SI unit(International System),
unit of mass is kg and unit of acceleration is m/s²
From F = m×a the unit of force is kg⋅m/s² which is known as Newton(N).
Newton(N) may be defined as that force which when applied to a body having a mass of one kilogram gives it an acceleration of one meter per square second. Kilogram gives it an acceleration of one meter per square second.
Kilo Newton(kN) and Mega Newton(MN) are recommended larger units.

•Weight: Weight is a force exerted by gravity
weight = Mass × Gravitational acceleration
            = m × g
the weight of a body is dependent upon gravitational force, so it is not constant.

ii) Mass: Mass is the quantity of matter and it is constant. It does not depend upon gravitational force.
The fundamental unit of mass is the Kilogram(kg). It is the mass of the platinum-iridium lump kept at SÈVRES, France.
Mathematically, mass;
m=(W/g) × kg 
where w is weight in N, g is the gravitational acceleration in m/s².

3. Pressure

Pressure is the property of the fluid and it is defined as force per unit area.
∴ Pressure = Force/Area or P = F/a  N/m².
The unit of pressure is N/m². N/m² is known as Pascal(Pa)
∴ 1 Pa = 1 N/m²
Kilo Pascal(kPa); Mega-Pascal(MPa) and bar ( 1 bar = 10⁵ Pa or N/m²) are recommended larger unit. 1 kg/cm² is approximately equals to 0.1 MPa.
The pressure measured by a pressure gauge is called gauge pressure.

• Pressure gauges, Manometers etc are used to measure gauge pressure and Barometer is used to measure atmospheric pressure.
• Atmospheric pressure is the pressure exerted by the atmosphere. It varies with location on earth.
• Standard atmospheric pressure is a pressure of atmospheric air at mean sea level. It is defined as the pressure developed by a mercury column of 760 mm. If we take the density of mercury equal to 13595.09kg/m³ and gravitational acceleration equals to 9.80665 m/s².
Standard atmospheric pressure will be
P = ρgh = 13595.09 × 9.80665 × 0.760 N/m²
              =1.01325 × 10⁵ N/m² or Pa
     P_atm = 1.01325 bar
•Absolute pressure is measured with reference to absolute zero pressure. It is the pressure related to perfect vacuum.
Mathematically,
Absolute Pressure = Atmospheric pressure + Gauge pressure 
•Vacuum is defined as the pressure below atmospheric pressure. A perfect vacuum is obtained when absolute pressure is zero, at this instant molecular momentum is zero. The relation between different pressures is given in Figure below.

In part 2, we will see work, power, energy, and heat