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Title: WORK , ENERGY AND POWER
Description: This is the simplest notes for physics chapter work , energy and power . It is best for the students who are studying in class 9,10,11 and 12..
Description: This is the simplest notes for physics chapter work , energy and power . It is best for the students who are studying in class 9,10,11 and 12..
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WORK, ENERGY AND POWER
(A) WORK, ENERGY AND POWER, THEIR MEASUREMENTS AND UNITS
WORK
In our daily parlance, the word 'work' is used for some sort of exertion
(physical or mental) or for various activities such as writing, reading or
eating; we say that we are doing work
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Work is said to be done only when a body moves under
the influence of a force
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MEASUREMENT OF WORK
The amount of work done on a body depends on two factors:
(i) the magnitude of the force applied, and
(ii) the displacement produced by the force
...
e
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Work is a scalar quantity
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If under some circumstances, a force displaces the body
in a direction other than the direction of force, then we can determine the
amount of work done by the force in either of the two ways:
(1) by finding the component of displacement of the body in the direction of
force, or
(2) by finding the component of force in the direction of displacement
...
Special cases
Case (i): If the displacement is in the direction of force, i
...
, θ = 0° deg then
cos 0° = 1
W=FxS
The work done is positive
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e
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W=0
Hence the work done is zero
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e
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The work done is negative
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Therefore, the
work done by the force of gravity on the body is
W = FS = mgh
Thus, work done by the force of gravity is same whether the body comes
down from a certain height using stairs or slope or a lift
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I
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I
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It is abbreviated as J
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Bigger units of work are kilo-joule (kJ), mega-joule (MJ) and giga-joule (GJ),
where 1 kJ = 10³ J, 1 MJ = 10⁶ J and 1 GJ = 10⁹ J
...
G
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unit: The C
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S
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Define 1 erg
1 erg of work is said to be done when a force of 1 dyne displaces a body
through a distance of 1 cm in its own direction
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Power is a scalar quantity
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If work W is done in time t, then
Power P = Work done W / Time taken t
Or P = W/t
P =F *v
Thus power spent by a source depends on the following two factors:
(1) the amount of work done by the source, and
(2) the time taken by the source to do the said work
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I
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I
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If 1 joule of work is done in 1 second, the power spent is said to be 1 watt
...
e
...
G
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Unit: The C
...
S unit of power is erg per second (er
Title: WORK , ENERGY AND POWER
Description: This is the simplest notes for physics chapter work , energy and power . It is best for the students who are studying in class 9,10,11 and 12..
Description: This is the simplest notes for physics chapter work , energy and power . It is best for the students who are studying in class 9,10,11 and 12..