 |
| Image :flickr |
The most popular equation in the world today is E=mc². Because this equation was the first to prove that the mass of an object has specific energy.
E=mc² is an equation in German physicist Albert Einstein's special theory of relativity. According to this equation, mass of an object can be converted to specific energy (or) energy can also be converted to mass.
To understand this, we first need to know about mass.
Mass - definition:
Mass is the most important measurement of an object. It refers to how much elements an object contains. Mass and weight are not the same thing. But they are both denoted by the same unit of Kilogram (Kg) .
The weight of an object varies from planet to planet. Because the weight of an object varies depending on the gravitational force of the planet where the object resides. But mass is a constant.
Consider measuring the mass of a cotton ball, a rubber ball, an iron ball, and all three. Which has more mass?
Definitely the iron ball. Because mass is a measure of how much matter an object contains. So mass is also related to the density of an object.
The mass of an average rain cloud is over several billion kilograms. But why didn't it fall down? This is because of the density. The density of a rain cloud is many times less than the density of an iron ball.
Therefore, if an object has more mass but less density, to our eyes it appears as a light object.
Method of measuring mass:
Various instruments have now been invented to calculate the weight of an object. But mass?
There are various methods for calculating mass. Here we will see a simple method among them. We have heard Newton's second law before. That is, the force acting on an object is equal to the product of the object's mass and its acceleration. This can be written as below.
F=ma
Here F is the force acting on an object, m is the mass of the object and a is the acceleration of the object. From this equation, the mass can be written as below.
m=F/a
Our weight generally refers to the force that the Earth can exert on us. Gravitational acceleration of Earth is 9.8×10⁸m/s. So, in the equation above, if you replace 'F' with your weight and replace 'a' with the value of Earth's gravitational acceleration, you can find your mass.
Now if your weight is taken to be 100 kg, then according to the above equation your mass will be 10.2 kg. This value is constant everywhere. But your weight may change depending on the gravitational acceleration of the planet you are on.
E=mc² Explanation:
Why we multiply a mass by square of the speed of light (c²) to get the energy form?
If you convert a certain mass of matter into energy, the converted energy travels at the speed of light. in the form of an electromagnetic wave. Hence the speed of light is used in this equation. But why is it squared?
In general, if an object is moving 4 times faster than another object, its energy is 16 times greater than that object. Here, it should be noted that the energy of the object is equal to square of its velocity. So in this equation the speed of light is squared.
Also, according to this equation E=mc², less mass is converted into more energy. For example, converting 1 gram of matter into energy is equivalent to the energy released from about 20 billion TNT bombs.
We have heard about different forms of energy like heat energy, kinetic energy etc. But this equation was the first to make it clear that there is an energy for mass. In this equation, E represents the mass-energy of an object.
Consider two inelastic objects of the same mass colliding with each other at the same speed. For example, consider two cars of equal mass colliding from opposite directions at equal speeds. And assume that these two cars are stuck together after the collision, at the point of collision.
Here, their kinetic energy before the collision is converted into their mass after the collision. So their mass would have increased by a certain amount. But this change will be very small. Perhaps, if these two cars had traveled at speeds equal to the speed of light, their mass would have increased enormously. But that is practically impossible.
Here, energy can be seen to be converted into mass. The equation E=mc² plays an important role in proving this phenomenon mathematically.
Here, this equation states that mass of an object can be converted to energy just as energy is converted to mass. Scientists have now discovered that when excess energy is released from an object, its mass decreases. So it is clear here that mass and energy are not different.
No method has yet been defined for the conversion of mass into energy. This is because the heat and pressure required to convert the mass of an object into energy is greater than the heat and pressure in the core of the Sun.