Question

Q.3
Derive expression for kinetic
energy using
Newton's second law
of
motion.​

Answer 1

Answer:

Expression for K.E - KINETIC ENERGY-K.E = 1/2 mv2. "Energy posses by a body by virtue of its motion is referred to as 'Kinetic Energy'". Kinetic energy depends upon the mass and velocity of body. If velocity is zero then K.E. of body will also be zero.Kinetic energy is a scalar quantity like other forms of energies.

Consider a body of mass "m" starts moving from rest. After a time interval "t" its velocity becomes V.

If initial velocity of the body is Vi = 0 ,final velocity Vf = V and the displacement of body is "d". Then

Using equation of motion

2aS = Vf2 – Vi2

Putting the above mentioned values

Explanation:

2ad = V2 – 0

a = V2/2d

Now force is given by

F = ma

Putting the value of acceleration

F = m(V2/2d)

As we know that

Work done = Fd

Putting the value of F

Work done = (mv2/2d)(d)

Work done = mV2/2

OR

Work done = ½ mV2

Since the work done is motion is called "Kinetic Energy"

i.e.

K.E. = Work done

OR

K.E. =1/2mV2.