The E Tutor - Conservation of Energy
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Transcript of The E Tutor - Conservation of Energy
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Conservation of
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Energy AND Conservation of Energy
Energy is the ability to make things change.
A system that has energy has the ability to do work.
Energy is measured in the same units as work because
energy is transferred during the action of work.
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Conservation of Energynergy AND Conservation of Energy
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The Law of Conservation of EnergyEnergy cannot be created or destroyed; it may be
transformed from one form into another, but the totalamount of energy never changes.
Law of Conservation of Energy
P.E K.E. P.E.K.E. Is energy lost?
No Energy is converted!
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Conservation of EnergyPotential Energy
Conservation of Energy
Potential energy exists whenever an object which has mass has
a position within a force field. The most everyday example of this is
the position of objects in the earth's gravitational field.
Potential Energy(joules) Ep = mgh
Mass (kg)
Height (m)
Acceleration ofgravity (m/sec2)
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Conservation of EnergyKinetic Energy:
Conservation of Energy
Kinetic Energy exists whenever an object which has mass is in motion
with some velocity. Everything you see moving about has kinetic energy.
The kinetic energy of an object in this case is given by the relation:
Ek = 1 mv2
2Speed (m/sec)
Mass (kg)
KineticEnergy(joules)
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Conservation of EnergyProve The Conservation of Energy:-
Now prove that the Conservation law holds good in the case of a
freely falling body.
Let a body of mass 'm' placed at a height 'h' above the ground, start falling
down from rest.
In this case we have to show that the total energy (potential energy + kineticenergy) of the body at A, B and C remains constant i.e, potential energy is
completely transformed into kinetic energy.
Law of Conservation of Energy
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Conservation of EnergyAt A :-
Potential energy = mgh
Kinetic energy = 0
[the velocity is zero as the object is initially at rest]
Total energy at A = P.E. + K.E.
Total energy at A = mgh .. (i)
At B :-
P. Energy = mgh
= mg(h - x) [Height from the ground is (h - x)]
PE = mgh - mgx
Kinetic energy The body covers the distance x with a velocity v.
we know that v2 - u2= 2aS . Here, u = 0, a = g and S = x
K. Energy = mgx
Total energy at B = P.E. + K.E.
Total energy at B = mgh(ii)
Law of Conservation of Energy
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Conservation of EnergyAt C :-
Potential energy = m x g x 0 (h = 0)
P. Energy = 0
For Kinetic energy
The body covers the distance h with a velocity v.
We know that v2 - u2 = 2aS Here, u = 0, a = g and S = h
Kinetic Energy = mghTotal energy at C = P.E. + K.E.
Total energy at C = mgh . (iii)
From equations (i), (ii) and (iii)
That the total energy of the body remains constant at every point.
Thus,
We conclude that Law of Conservation Of Energy
Holds good in the case of a freely falling body
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Law of Conservation of Energy
