First, let's see what is the ourpose of Einstein's theory of relativity. Well, it helps an astrophysicist to calculate the trajectory of a galaxy, because at such a large speeds an distances relativistic effects are very important. Than he earns some mony for his calculations, which he uses to buy a car and a flat, so he can get laid. In essence, Einstein's theory's purpose is to get laid.
Geometry of Lobachewsky is about curved space. It is useful for another astrophysicist, to calculate effects of passege of a small black hole next to our solar system, and its effects on our space-time. He will get some mony for his calculations from the agency he works for, so that he can buy a car and a flat, and get laid. In essence, geometry of Lobachewsky is used just to get laid.
And finnaly, let's see what is the burpose of calculus. Well, calculus studies behaviour of systems during some period of time depending on various variables. An engineer employed in hydroelectric power plant uses it to calculet the production of electricity, which depends on the rate of flow of the water through turbines, ammount of water in accumulation etc. It is impossible without calculus. Of course, our engineer won't do this just like that. He will earn money from company he works for, so that he can buy a car and a flat, where he can get laid. In essence, the purpose of calculus is getting laid.
If you want to now more about other scientific disciplines and their purposes contact us at email@example.com. But, sincerely, we suppose that you already now the answers.
Proffessor: "To get laid!"