For scientists, energy is not really “something” that can be described as being “made of something” in the way we think, like a house made of bricks.
If it is not something tangible, then what is energy? Energy is like a capacity. This capacity refers to the ability to do something.
A musician has the ability to compose music; similarly, a painter has the ability to create art. Energy is the capacity of an object to perform a task.
An object performs a task when it applies a force to another object, pushing that object to move in a certain direction. What does this mean?
To answer this question, let’s imagine a person throwing a ball towards you, and you hit the ball with a bat. When the bat strikes the ball, it changes the speed and direction of the ball’s movement.
When you hit a ball with a bat, the bat transfers some of its kinetic energy to the ball to change its speed and direction (Image credit: Getty).
Energy is the ability that the bat has to change the direction of the ball. When the bat is swung, it can alter the path of any ball it strikes.
When you swing the bat, you transfer energy stored in your muscles to the bat. The harder you swing, the more forceful the bat becomes, and the more energy it carries.
Types of Energy
There are many ways an object can act, which means there are different types of energy.
As mentioned earlier, one type is the upward motion of the bat. This type of energy is called kinetic energy. It is the energy that an object possesses due to its motion.
Another type of energy is potential energy. Potential energy is the ability of an object to perform a task thanks to its position relative to other objects. This means that placing objects in certain positions gives them energy.
Let’s consider a fun example: imagine placing a bowl of water on a slightly ajar door; when someone pushes the door and steps in, the bowl will fall on their head.
Since the bowl is on the door, it has the potential to fall. And when it does fall, it can cause something to happen. Besides wetting the person who walks through the door, it also hits their head. Thus, the bowl has the capacity to perform a task simply because it is on the door, not because it is moving. That capacity of the bowl is potential energy.
If you position a bowl of water steadily on a door, you give the bowl potential energy. When the door opens, the bowl begins to fall, “causing trouble” for anyone unfortunate enough to open that door (Image: Shutterstock).
Einstein’s Famous Equation
The brilliant physicist Albert Einstein devised an equation about energy that you may know: E=mc².
In this equation, E stands for energy, m stands for mass, and c is the speed of light.
This equation states that energy equals mass multiplied by a certain number. So, is energy not made up of something? Not necessarily, because some massless objects can still possess energy. For example, light. We know that light has energy because we capture light energy in solar panels and convert it into electrical energy.
However, light is made up of incredibly small particles called photons, and photons have no mass.
Thus, if energy is produced by mass, then light would have no energy. This creates a mystery about solar energy. But it turns out that although light has no mass, it still possesses something called momentum, which enables it to do work or perform a task.
Mass, Energy, and Momentum
There is a more complex version of the equation that Einstein devised, which shows the relationship between mass and momentum.
Light travels at incredible speed, reaching Earth from the sun in just over 8 seconds (Image: Shutterstock).
One very important thing we need to know is that light travels extremely fast. Because the amount of energy in an object depends on the mass of that object multiplied by the square of the speed of light, even a small amount of matter carries a vast amount of energy.
In just 1 second, light travels nearly 300 million meters, meaning that one kilogram of mass is equivalent to nearly 9 million trillion joules (J) of energy, or the number 9 followed by 18 zeros: 9,000,000,000,000,000,000 J.
The challenge lies in how to release that energy. This truly requires the workings of nuclear bombs and nuclear energy: they release the energy contained in matter to create an enormous effect/energy.
