4. WORK
Work is said to be done only when
a body undergoes displacement
under the action of a force
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5. If a force of F newton is applied
continuously on a body undergoes a
displacement of s metre in the
direction of the force, then the work
done by the force is …
W = Fs
Unit of work is joule
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11. KINETIC ENERGY
The energy possessed by a body by
virtue of its motion is the kinetic
energy
When a body moves with a velocity
v its kinetic energy is
K = ½ mv2
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12. POTENTIAL ENERGY
The energy possessed by a body
due to its position or strain is
the potential energy.
Potential energy,
U = mgh
m → mass of object
g →acceleration due to gravity
h → height
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13. EXAMPLES…
POTENTIAL ENERGY
Water in dam
Elongated rubber
band
Stretched bow
Water in a tank etc.
KINETIC ENERGY
Running train
Mango falling from
tree
Flowing river
Flying bird etc.
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14. LAW OF CONSERVATION OF ENERGY
Energy can neither be created
nor destroyed. One form of
energy can only be converted to
another form.
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