elements of mechanical

1.  PREPARED BY :-
UTKARSH GANDHI (23)
DIGVIJAYSINH GOHIL (28)
RUT PARIKH (29)
 GUIDED BY :-
RAHUL SIR

2.  Prime mover is an engine or device through
which we can convert natural source of
energy in to mechanical work.

3. Source of
energy used
by prime
movers
Thermal
Fuels Nuclear
Geother
mal
Biogas Solar
energy
Non Thermal
Water Tidel Wind

4.  Newton’s second law of motion defines the force
acting on a body. The unit of Force is Newton(N).
When a force of 1 Newton is applied to 1 kg of
mass, it produces acceleration of 1 m/s².
1 N = 1 kg m/s²
 The weight (W) of a body is the force with which the body is
attracted to the centre of the earth. It is a product of mass of
the body and local gravitational acceleration (g).
W = mg
 The value of g at sea level is 9.80663 m/s².

5.  Pressure is defined as the normal force exerted by
a system against unit area of the bounding surface.
 The pressure p at a point in a fluid in equilibrium is
the same in all directions.
 In SI system of units , the unit of pressure is
Pascal(Pa). One Pascal equals to force of one
Newton acting on an area of 1 m².
 The other units of pressure are ‘bar’ and ‘standard
atmosphere’.
 1 bar = 10⁵ Pa = 100kPa = .1MPa .
 1 atm = 101.325 kPa = 1.01325 MPa .

6.  Energy is defined as capacity to exert force
through a distance. It exists in many forms.
 Engineering processes involve the conversion
of energy from one form to another.
 The unit of energy in SI system of units is Nm
or Joule(J).
 The energy per unit mass is called the
specific heat. Its unit is J/kg.

7.  Rate of energy transfer is known as power. Its unit
is watt(W). It is a small unit and very often
kilowatt(kW) and megawatt(MW) is used.
 1 W = 1 J/s = 1 Nm/s .
 The power developed by an engine termed as
‘indicated power’. The power available at the shaft
of engine is turned as ‘brake power’.
 The power loss due to friction, pumping etc in an
engine is termed as ‘friction power’.

8.  A thermodynamic system is defined as a
quantity of matter or a region in a space upon
which attention is focused for the analysis of
the problem.
 Everything external to the system is called
‘surrounding’ or the environment.
 A system and its surrounding together forms
a ‘universe’.

9.  System can be classified in three categories
1.] Closed System
2.] Open System
3.] Isolated System.
 Closed system is the one in which there is no mass
transfer across the boundary of the system thus it
is a system of fixed mass. Energy transfer can be
there across the boundary.
 Open system is the one in which both mass and
energy cross the boundary of the system.
 An isolated system is the one in which neither
mass nor energy cross the boundary of system.

10.  It is a quantitative measure of the degree of
coldness or hotness of a system. It’s unit in SI
system of unit is Kelvin(K), Other units of
temperature are Degree centigrade (˚C) and
Degree Fahrenheit (˚F).
 K = ˚C + 273.16
 ˚C = 5/9(˚F-32)

11.  The amount of heat required to raise the
temperature of 1 kg of mass by 1 ˚C or 1 K is
termed as specific heat of the substance. It is
denoted by c.
 If Q is amount of heat required in (J), to raise the
temperature of m kg of mass by ∆t K then specific heat
can be written as
c = Q/m∙∆t J/kg K .

12.  Gases have two specific heats. Which are at
constant pressure(Cр) and constant volume(Cv).
 The product of mass and specific heat is called the
heat capacity of the substance.

13.  The P-V diagram for water is given below and the
P-V diagram for other then water is given below.

14.  Melting point:- It is the temperature at which the
solid is converted into liquid when heat is supplied.
 Boiling point:- It is the temperature at which the
liquid is converted into vapor when heat is
supplied
 Critical point:- It is the temperature and pressure
above which only one phase is existing.
 Triple point:- Triple point of a substance refers to
the state at which substance can coexist in solid,
liquid, gaseous phase in equilibrium. For water it is
0.01 0C at this temp. ice, water, and steam can
coexist in equilibrium.

15. PROCESS , PATH & CYCLE
 Process:- An change that a system undergoes from one
equilibrium state to another is known as a process.
 Path:- Path is the series of state through which a
system passes during a process. The process path
indicate a series of equilibrium state through which the
system asses during a process.
 Cycle:- A system is said to have undergone a cycle if it
returns to its initial state at the and of the process.
Hence for a cycle the initial and final state are identical

16.  When heat (Q) is supplied to a body, some amount of
heat is converted into external work (W) due to
expansion of fluid volume and remaining amount of
heat causes either to increase its temperature or to
change its state. Internal energy is one type of energy
which is neither heat nor work, hence it is stored form
of energy. It is denoted by U.
 Mathematically,
Q = W + U ,
where Q is amount of heat, W is work and U is internal
energy.

17.  Enthalpy is a thermodynamic property of fluid,
denoted by H. It can be defined as the summation
of internal energy and flow energy. Enthalpy of a
substance at any point is qualification of energy
content in it.
H = U + pV
U- internal energy
pV- flow of energy

18.  Zeroth law of thermodynamic states that if the
bodies B and C are in thermal equilibrium with a
third body A separately then two bodies B and C
shall also be in thermal equilibrium with each
other.
 This is the principle of temperature measurement.

19.  This law state that energy can neither be created nor
destroyed, it can be converted from one form to
another form.
 First law may be expressed as,
Change in total energy = net energy transferred as heat
and work .
E = Q-W
E is a summation of various energies like internal energy,
kinetic energy, potential.
 In closed system , mass is fixed and there is no
elevation difference and movement. KE=0 AND PE=0
U = Q – W for cyclic process E=0
Q – W = 0

20. THANK YOU