physics abc about energy 03

Physics ABC - About Energy 03

2021-06-03

Conservation of Energy

1. Law of Conservation of Mechanical Energy

Kinetic energy, gravitational potential energy, and elastic potential energy are collectively referred to as mechanical energy.

In a system where only gravity or elastic force does work, kinetic energy and potential energy can be transformed into each other, while the total mechanical energy remains unchanged. This is called the law of conservation of mechanical energy.

Law of Conservation of Mechanical Energy is a part of Conservation of Energy.

2. Law of Conservation of Energy

In addition to mechanical energy, energy also has other ways of existence, such as internal energy (also called thermal energy, related to temperature), chemical energy (energy released or absorbed through chemical reactions), electrical energy (related to electromagnetics that will be learned later) , Nuclear energy (energy stored in the nucleus, released through nuclear reactions), etc.

Energy will neither be produced out of thin air, nor will it disappear out of thin air. It can only be transformed from one form to another, or transferred from one object to another. In the process of transformation or transfer, the total amount of energy remains unchanged. change. This is the Law of Conservation of Energy.

Energy Efficiency

The amount of useful enerty produced in comparised to the amount of total energy used.

% Efficiency = (Eout / Ein) * 100%

What is Power?

The work done per unit time is called power, which is used to express the speed of work done.

Power is usually represented by P.

P = W / t (W is work)

The unit of power is watts, and the symbol is W.

1 W = 1 J/s (W is watts, J is Joule, s is second)