If conservation of energy is true then how much energy (including all kinds of radiation and kinetic and potential) is there on earth since it was born?
Answers
Answer:
In physics, the term conservation refers to something which doesn't change. This means that the variable in an equation which represents a conserved quantity is constant over time. It has the same value both before and after an event.
Energy, as we'll be discussing it in this article, refers to the total energy of a system. As objects move around over time, the energy associated with them—e.g., kinetic, gravitational potential, heat—might change forms, but if energy is conserved, then the total will remain the same.
Conservation of energy applies only to isolated systems. A ball rolling across a rough floor will not obey the law of conservation of energy because it is not isolated from the floor. The floor is, in fact, doing work on the ball through friction. However, if we consider the ball and floor together, then conservation of energy will apply. We would normally call this combination the ball-floor system.
E_\mathrm{Ki} + U_\mathrm{gi} + U_\mathrm{si} = E_\mathrm{Kf} + U_\mathrm{gf} + U_\mathrm{sf} + E_\mathrm{Hf}E
Ki+Ugi +Usi =EKf +Ugf +Usf +EHf
Which could be expanded out as:
\frac{1}{2}mv_i^2 + mgh_i + \frac{1}{2}kx_i^2 = \frac{1}{2}mv_f^2 + mgh_f + \frac{1}{2}kx_f^2 + E_\mathrm{Hf}