Page 10 - 9-phy-6 Work and Energy

6. Work and Energy eLearn.Punjab

6.4 POTENTIAL ENERGY

Often a body has the ability to do work although it is at rest. For example, an apple on a tree is
capable to do work as it falls. Thus, it possesses energy due to its position. The kind of energy
which a body possesses due to its position is called its potential energy.

The energy possessed by a body due to its position is known as its potential energy.

Stored water possesses potential energy due to its height. A hammer
raised up to some height has the ability to do work because it
possesses potential energy. A stretched bow has potential energy
due to its stretched position. When released, the stored energy of the
bow pushes the arrow out of it. The energy present in the stretched
bow is called elastic potential energy.

The potential energy possessed by a hammer is due to its height.
The energy present in a body due to its height is called gravitational
potential energy.

Let a body of mass m be raised up through height h from the ground.
The body will acquire potential energy equal to the work done in
lifting it to height h.

Thus, the potential energy possessed by the body at height h with Figure 6.5: (a) Hammer raised up
respect to the ground is mgh and is equal to the work done in lifting (b) stretched bow, both possess
it to height h.
potential energy.
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