Momentum vs. Energy

Difference Between Momentum and Energy

Momentum and energy the laws of motion invented by Newton. These are the properties of an object in a movement. Momentum is explained as the product of velocity and mass of the moving object. Kinetic energy is the half of product of the square of velocity and mass. When a moving object’s velocity is increased, the momentum will be increased. Its kinetic energy will also be increased. It should be kept in mind that kinetic energy and momentum are not interchangeable.

As Newton’s second law of motion states, the product of velocity and mass of a moving object is called momentum. According to this law, the momentum’s rate of change is directly proportional to the force which is applied to it which is in the direction of the force. It can be expressed by the formula:

P = mv

As we know that kinetic energy of a moving object is half of the product of square of velocity and the mass. It can be expressed by the formula:

Kinetic Energy = ½ mv²

Energy and momentum depend upon velocity of a moving object. If the velocity is doubled, the momentum will be doubled and the kinetic energy will be quadrupled. The difference can be understood with an example.

If one comes in front of a moving iron ball weighing 1 kg at the speed of 1 km/sec., what will happen? If one comes in front of truck at the same speed, what will happen? The truck at that speed will through a person away and chances are that one may be saved. But a moving iron ball at that speed certainly will kill him. Let us understand it with the formulas:

P (truck) = 1000 ×1= 1000kg m/s

Kinetic Energy of truck = ½ ×10000 ×1× 1 = 500 joules


P (meatball) = 1 ×1000 = 1000 kg m/s

Kinetic Energy of meatball = ½ × 1 × 1000 × 1000 = 500000 Joules

Through this example it is understood that it is dangerous for a man to stand against the iron ball is more dangerous than standing in front of a moving ball as it has high Kinetic energy.


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