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what is kinetic energy

It is the energy possesed by a body by virtue of its motion.

Expression for the kinetic energy of a moving body:

Consider a body of mass m, moving with a velocity v. Its kinetic energy is equal to the workdone by an external agency in increasing velocity from zero to v.

Let a constant force F act on the body at rest and move it through a distance S, there by changing its velocity to v. Let a be the constant acceleration produced. Then

v² = u² + 2as

v² = 2as

a = v² / 2as

Force, F = ma

                = mv²/2as

Workdone, W = F x S

                           = (mv²/2as) x S

                           = 1/2 mv²

Kinetic energy of the body = (1/2) mv²

• K.E is always a scalar quantity.

• The K.E depends on the frame of reference.

• K.E is related to momentum p as K = p²/2m, where m is the mass of the body.