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# Tag Archives: 2m

## Momentum and Kinetic Energy

Two bodies one light and other heavy have equal momentum.Which of them has higher kinetic energy?

(Aajma Manoj asked)

Answer:

The lighter body will have greater kinetic energy.

Explanatiom

Momentum, p=mv

squaring both sides, p^{2} = m^{2}v^{2}

Kinetic Energy = 1/2 mv^{2} = p^{2}/2m

Therefore, for bodies of equal momenta, kinetic energy is inversely proportional to mass.

## Numerical Problem from Laws of Motion

An 8000 kg engine pulls 40000 kg train alonged a level track and gives an acceleration of 1.2m/s2. Find the accelaration produced by same engine on a train of mass 16000kg?

**Answer**:

Force exerted by the engine = mass of train x acceleration = 40000 x 1.2=48000N

When the same engine pulls a 16000 kg train, the acceleration = 48000/16000=3m/s2