Define and derive formula for potential and kinetic energy

Dear Student,
•Kinetic energy -
The energy possessed by virtua of its motion is said to be kinetic energy. SI unit of kinetic energy is joule (J).
                                          K E = 1/2mv2

Derivation : we know that

W = f x s

but f = ma

W = mas......-> Eqn 1

By 3rd Eqn of motion

v2 = u2 + 2as

at rest u=0

v2 = 2as

as = 1/2 v2

Putting in Eqn 1

W = 1/2 mv2

Since work done is stored in kinetic energy.

so,                        K E = 1/2 mv2


• Potential Energy -
The energy possessed by virtua of its position is said to be potential energy. SI unit of potential energy is joule (J).
                                      P E = mgh

Derivation: we know that

W = f x s ....Eqn 1

when the object of mass m is lifted at a height h then,

F = mg and

s = h

then Eqn 1 becomes

W = mgh

Since work done = P E

so,              P E = mgh

Regards

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