“Energy posses by a body by virtue of its motion is referred to as ‘Kinetic Energy’”.
K.E. = 1/2 mv2
Kinetic energy depends upon the mass and velocity of body. If velocity is zero than K.E. of body will also be zero.
Kinetic energy is a scalar quantity like other forms of energies.
DERIVE: K.E = 1/2 mv2
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
First we will find the acceleration of body.
Using equation of motion
2aS = Vf2 – Vi2 Putting the above mentioned values 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.