ENERGY : THE DRIVING FORCE
1.)Work: Work is the product of the force
acting on the body and the displacement
of the body. When the force (F) acting on
the body and the displacement (s) of the
body have the same direction, the work
done by the force is W=Fs.
Work has magnitude ,but not dirction.
Thus, it is a scalar quatity. The SI unit of
work is the joule (J) and CGS is the
erg.
1jooule=1 newton *1 metre
1J =1Nm
1 erg =1 dyne* 1 centimetre
= 1 dyne. centimentre
1 J = 10 ergs
2.) Positive , negative and zero work:When
the force acting on the body and the
displacement of the body have the same
direction. When thhe force done by the force is
ment have opposite directions, the force and
displacement are perpendicular to each
other ,the work done ;is zero.
3).Energy: Energy is the capacity to do
work. It is a quantity. Its units are
the same as the units of work ,i.e.,the
joule (SI units) and the erg (CGS unit).
4).Kinetic energy: The energy possessed by
a body by the virtue of its motion is called
the kinetic energy. THe kinetic energy of a
body of mass m, moving with velocity v is
1-2 mv.
5.) Potential energy: The energy possessed
by a body due to its shape or position or
configuration is called the potential energy
of a body of mass m raised to a height h
above the ground level is mgh, where g is
the magnitude of the accerleraction due to
gravity at that position..
6.) Different forms of energy: Mechamical
energy ( potential energy and kinetic
energy ) , heat ,light , sound, electrical
energy ,solar energy , chemical energy,
nuclear energy , etc ., are different forms of
energgy . Energy can be converted from one
form to another.
7.) Law of conservation of energy: Energy
can neither be created nor be destroyed,
It can be converted from one form to
another. The total amount of energy in the
universe always remains contant.
8.) Power: Power is the rate of doing work.
If W is the work done .in time t, power (P) is
given by p=W-t . It is a scalar quantity. The
SI unit of power is the watt(W) and CGS
unit is the erg per second.
1watt = 1joule per second
10 erg per second
( 1 joule =10 ergs)
Power is also measured in unit horse-
power ( used in industry ).
I horesepower (hp) = 746 watts.
The kilowatt hour is a unit of energy
used for commercial purpose.
I kilowatt hour (kWh) = 3.6 * 10 J
The electrical energy used in house,
industry ,commercial establishment , etc,.
is expressed in KWh.
1.)Work: Work is the product of the force
acting on the body and the displacement
of the body. When the force (F) acting on
the body and the displacement (s) of the
body have the same direction, the work
done by the force is W=Fs.
Work has magnitude ,but not dirction.
Thus, it is a scalar quatity. The SI unit of
work is the joule (J) and CGS is the
erg.
1jooule=1 newton *1 metre
1J =1Nm
1 erg =1 dyne* 1 centimetre
= 1 dyne. centimentre
1 J = 10 ergs
2.) Positive , negative and zero work:When
the force acting on the body and the
displacement of the body have the same
direction. When thhe force done by the force is
ment have opposite directions, the force and
displacement are perpendicular to each
other ,the work done ;is zero.
3).Energy: Energy is the capacity to do
work. It is a quantity. Its units are
the same as the units of work ,i.e.,the
joule (SI units) and the erg (CGS unit).
4).Kinetic energy: The energy possessed by
a body by the virtue of its motion is called
the kinetic energy. THe kinetic energy of a
body of mass m, moving with velocity v is
1-2 mv.
5.) Potential energy: The energy possessed
by a body due to its shape or position or
configuration is called the potential energy
of a body of mass m raised to a height h
above the ground level is mgh, where g is
the magnitude of the accerleraction due to
gravity at that position..
6.) Different forms of energy: Mechamical
energy ( potential energy and kinetic
energy ) , heat ,light , sound, electrical
energy ,solar energy , chemical energy,
nuclear energy , etc ., are different forms of
energgy . Energy can be converted from one
form to another.
7.) Law of conservation of energy: Energy
can neither be created nor be destroyed,
It can be converted from one form to
another. The total amount of energy in the
universe always remains contant.
8.) Power: Power is the rate of doing work.
If W is the work done .in time t, power (P) is
given by p=W-t . It is a scalar quantity. The
SI unit of power is the watt(W) and CGS
unit is the erg per second.
1watt = 1joule per second
10 erg per second
( 1 joule =10 ergs)
Power is also measured in unit horse-
power ( used in industry ).
I horesepower (hp) = 746 watts.
The kilowatt hour is a unit of energy
used for commercial purpose.
I kilowatt hour (kWh) = 3.6 * 10 J
The electrical energy used in house,
industry ,commercial establishment , etc,.
is expressed in KWh.
