Question

Define Kinetic Energy, write an example. Derive formula for it.

Answer 1

Answer

In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.

Explanation:

Consider a body of mass "m" moving with an initial velocity "u".

A constant force "F" acts on it and the velocity changes to "v".

Let "s" be the distance covered and "a" be the constant acceleration

We know that

v² - u² = 2as

s = \frac{v^{2} - u ^{2} }{2a}

2a

v

2

−u

2

We know that ,

Work done = Force(F) × displacement (s)

F = ma

W = ma ×\frac{v^{2} - u ^{2} }{2a}

2a

v

2

−u

2

["a" gets cancelled ]

W = m ×\frac{v^{2} - u ^{2} }{2}

2

v

2

−u

2

= \frac{1 }{2}

2

1

m[v² - u² ]

When , initial velocity , u = 0

W = \frac{1 }{2}

2

1

mv²

K.E = Work done

= \frac{1 }{2}

2

1

mv².

Answer 2

Work done by the Body on virtue of Motion is called Kinetic energy.

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