Question

With an example, derive the expression for the kinetic energy of a moving body.

Answer 1

Answer:

ANSWER

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.

Derivation:

Let us consider an object of m which is at rest lying on a table.

Let A force F acts on the object which moves the object through a distance S.

The workdone=F×S

W=F

net

×S-------(1)

Let the work done on the object causes a change in its velocity from u to V and let a be the acceleration.

From Third equation of motion:

V²−u²=2as

s=V²−u²/2a----------(2)

By Newton's Second law:

F=ma------(3)

From equation (1), (2) and (3)

W=ma×(V

2

−u

2

/2a)=(1/2)m(V

2

−u

2

)

As we assumed object at rest, u=0

W=(1/2)mV

2

we know that the kinetic energy of a body moving with a certain velocity is equal to work done on the object to acquire that velocity from rest.

∴K.E=1/2mV

2

Answer 2

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• The energy possessed by an object due to its motion is called as kinetic Energy. Derivation: Let us consider an object of mass " m " which is at rest on smooth horizontal plane. Let a Force , F acts on the object and let the object from rest moves from point A to point B and covers a displacement S.

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