動能與勢能

During your physics class, your teacher had already introduced to you the differences between kinetic energy and potential energy. This time, let us have a refresher on what kinetic and potential energies are all about in simpler terms. When there is motion or movement, there is kinetic energy. In other words, kinetic energy is the energy of motion. If you have a moving object, the energy it possesses is kinetic energy. Remember the formula  ½ mv2? It is the formula for kinetic energy. In your physics class, it is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. When a moving object hits something, work can be done.

The word “kinetic” comes from the Greek word “kinetikos” meaning “motion.” Gottfried Leibniz and Johann Bernoulli developed ½ mv2. As they said, kinetic energy is the living force. But the first one to coin the term “kinetic energy” was William Thomson later Lord Kelvin.

In our everyday life, we always see kinetic energy being applied. If you are in school and you see your teacher writing on the board, there is kinetic energy. The mere movement of her hands is also kinetic energy. If your pencil falls and you pick it up, you are exhibiting kinetic energy. If you are playing basketball with your friends, you are possessing kinetic energy.

On the other hand, potential energy is energy at rest. During your physics class, potential energy is defined as the energy of an object or a 系統 due to the position of the body or the arrangement of the particles of the system. Everything has the capacity to do work, but several objects are at rest. When triggered, these objects can do work. Back in the 19th century, the term “potential energy” was coined by William Rankine, a physicist and a Scottish engineer. In his concept of potential energy, it showed records that link it to the original potentiality concept of the Greek philosopher Aristotle.

To make this clearer for you, here are a few examples of potential energy applied in our everyday lives. If you are just standing beside the road, you are exhibiting potential energy. Another example of it is a sandwich on top of your dining table. It doesn’t move, but when your cat pushes it to fall down off the table, that falling sandwich will exhibit kinetic energy. Another good example of potential energy is the 水 at a closed dam. The 水 just stay still inside the dam. But when the authorities release the water from the dam, it will exhibit kinetic energy.

You see, physics doesn’t have to be that complicated. If you understand kinetic energy and potential energy, you can identify what kind of energy is being possessed by that object. If an object is in motion, it is kinetic energy. If an object is at rest, it is potential energy.

This article aims to differentiate kinetic energy and potential energy. In your next pop quiz, we are hoping that you can identify which is which.

Summary:

1. 動能是運動的能量，而勢能是靜止的能量。
2. “動能”一詞是威廉·湯姆森創造的，而“勢能”則是威廉·蘭金創造的。
3. 動能的例子有：老師在黑板上寫字，拿起鉛筆，打籃球。勢能的例子有：站立，桌子上的三明治，封閉水壩的水。
4. 當對靜止物體施加足夠的能量時，它的勢能就會轉化為動能。