Question

Derive an expression for kinetic energy of a body ?

Answer 1

suppose 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

2as =v^2 - u^2

s =  = v^2-u^2/2a

We know that ,

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

F = ma

W = ma × v^2-u^2/2a

["a" gets cancelled ]

W = m × v^2-u^2 /2

= 1/2( m[v² - u² ] )

When , initial velocity , u = 0

W = 1/2 mv²

K.E = Work done

= 1/2 mv²

Answer 2

Answer:

Suppose a body of mass m is moving with velocity v it is brought to rest by applying retarding force f suppose it travels a distance from coming to rest kinetic energy of body k = work done by retarding forced to stop it.