FUNDAMENTAL CONCEPTS
OF
•
Work
is said to be done when the application of a force produces a change in the body.
The change may be in
position, velocity, shape, chemical composition, temperature or colour of the object.
•
Work is a scalar quantity (i.e. no direction is required) and the SI unit of work is the
Joule
(
J
).
1
1
1
1
2
2
J
N
m
J
k g
m
s
=
⋅
⇔
=
⋅
•
The mechanical work done by a force is equal to the product of the component of the force along the direction of
the motion of the object and the distance through which the point of application of the force moves.
Mathematically,
W
F
d
W
F
d
=
⋅
⇔
=
→
→
→
→
∆
∆
c o s
θ
where
is the angle between the force and the displacement
vectors.
The work done can also be found using the
area
under a
force
versus
displacement
graph (regardless of
the shape of the force–displacement function).
•
Energy
is the capacity (ability) to do work.
The units of energy are the same as work.
•
The energy possessed by an object by virtue of its motion is called
kinetic energy
.
Mathematically,
K
m
v
=
1
2
2
.
•
The energy possessed by an object die to its position or change of shape is called
potential energy
.
When a body of
mass
m
is raised through a vertical height
h
under the influence of gravity, then the body attains
gravitational
potential energy
.
Mathematically,
U
m
g h
=
.
•
Conservation of
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 Spring '09
 TANNY
 Calculus, Energy, Force, Potential Energy, Work

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