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Transformation of Energy

The motion of a pendulum is a classic example of mechanical energy conservation. A pendulum consists of a mass (known as a bob) attached by a string to a pivot point. As the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

The pendulum swings down, changing its gravitational potential energy into kinetic energy. Then, as it swings up, the kinetic energy changes back into the gravitational potential energy.

Since there are no external forces doing work, the total mechanical energy of the pendulum bob is conserved. The conservation of mechanical energy is demonstrated in the animation below. Observe the KE and PE bars of the bar chart; their sum is constant 


Observe that the falling motion of the bob is accompanied by an increase in speed. As the bob loses height and PE, it gains speed and KE; yet the total of the two forms of mechanical energy is conserved.

Activity : Discuss some examples of following energy transformations to your classmates and teachers.

(a) Thermal to electrical.

(b) Chemical to heat.

(c) Electric to heat and light.

(d) Electric to sound.

(e) Strain energy to kinetic energy.

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Sources of energy

Types of energy

Forms of energy

Energy Conservation

Transformation of energy

Measurement of energy



Combustion engines

Joule's experiment

Fun Facts