Hi everyone, this is my new blog. In my blogs, I will be talking about physics as you may have guessed from the title, and I hope this will help you.
Many of you know Einstein's most popular equation, e=mc squared, but do you know what it means? Well, let me tell you what it means. E stands for energy, M for mass and C stands for speed of light (which is 300 million metres per second). What this means is that the total amount of energy an object has is its mass multiplied by the speed of light squared. For example, 2 kg of water will have an enery of :
2 x c squared (300,000,000 x 300,000,000) = 1,800,000,000,000,000,000, Joules
( A Joule equals approximately the energy of a 1kg text book dropped from a height of 1.5 metres)
That's a lot of energy (enough to blow up 4 or 5 cities)!! Now, you might be thinking how could water have so much energy? Well this is the best way to explain :
- Hydrogen is the basic element which makes all other elements. A hydrogen atom consists of a proton and a neutron in the nucleus and an electron orbiting the nucleus. The process of making other elements using hydrogen is called fusion (that fuses two or more hydrogen atoms together). This process happened in the big bang and still happens in stars that are about to die.
- If you slam two hydrogen atoms together, you will create a helium atom which consists of two protons, two nuetrons and two electrons. If you slam three hydrogen atoms together you will create a lithium atom which consists of three protons, nuetrons and electrons each. The more hydrogen atoms you slam together, the more different types of elements you make, until you reach elements like uranium which have more than 90 nuetrons, protons and electrons.
- Now, if you can fuse hydrogen atoms together to form other elements, you can also seperate other elements to make hydrogen (using a process called fission). Note that in the process of fusion or fission, the matter does lose or gain mass.
- Like I said before, all elements are made up of hydrogen, and therefore one can say that an object that weighs n grams is made up of n grams of hydrogen. (I know this sounds a bit weird but lets all stick to this)!!
- As you know, when a hydrogen atom splits, it creates an immense amount of energy (like what happens in an atomic bomb). An atomic bomb contains about 2 party balloons of hydrogen ( imagine this blowing up a whole city)!! This gives you an idea of the amount of energy hydrogen atoms have.
- Using fission, if you completely convert all othere elements of an object into hydrogen, and blow it up (like an atom bomb), you would find out exactly how much energy that object has (you can call this potential energy).
So, how does that 2 kg of water have that much energy? Refer to the first two paragraphs in case the information was too heavy to stay on!!
Well the composition of water is H2O, so if you take out all hydrogen atoms and convert oxygen back into hydrogen and blow it up, you would find out that the water has enough energy to blow up 4 or 5 cities! Be careful though, stand at least at a 200 km radius or you will be evaporated!!
So now I hope you understand the meaning of e=mc squared.
PS: Despite all this, I am still wondering how Einstein came up with c, the speed of light.
Do write back....I will post another blog soon!
