#EnergyExplained #WhatIsEnergy #UnderstandingEnergy
Have you ever wondered what exactly energy is? 🤔 It’s more than just the ability to do work – it’s the very essence that powers our world! Let’s break it down for you in simple terms and real-life examples. 💡
##The Basics of Energy
Energy is the life force that allows things to happen. It comes in many forms, such as kinetic energy (energy of motion), potential energy (stored energy), thermal energy (heat), and light energy. Simply put, energy is what makes things happen – from a ball rolling down a hill to the sun shining in the sky. 🌞
##Understanding Energy Types
1. **Kinetic Energy**: Think of a moving car or a flying bird – that’s kinetic energy in action!
2. **Potential Energy**: Picture a stretched rubber band or a raised hammer – that’s potential energy waiting to be released!
3. **Thermal Energy**: When you feel the warmth of a campfire or a cup of coffee, that’s thermal energy giving off heat.
4. **Light Energy**: The glow of a light bulb or the rays of the sun are examples of light energy.
##How Energy Works
Energy cannot be created or destroyed – it can only be transformed from one form to another. This is known as the law of conservation of energy. For example, when you eat food, your body converts the energy from the food into the energy you need to move, think, and breathe. 🍎
##The Impact of Energy
Energy is essential for everything we do, from powering our homes and cars to fueling our bodies and brains. Without energy, life as we know it would come to a standstill. That’s why it’s crucial to understand how to conserve and use energy wisely to sustain our planet for future generations. 🌍
In conclusion, energy is the driving force behind everything in the universe. By understanding the different types of energy and how they work, we can harness the power of energy to make positive changes in our lives and the world around us. So next time you flip on a light switch or take a sip of coffee, remember the incredible force that is energy! ⚡
So, what do you think energy is now? Feel free to share your thoughts and questions in the comments below! Let’s keep the conversation going. 💬
While it seems unrelated, I think this video is very relevant:
It’s part of an interview with Richard Feynman, in which he was asked about what magnetism is. His answer discusses how the problem with this sort of question is that the answers can keep being broken down with more questions until you eventually get to the real answer: that’s the way things are.
The most fundamental definition of energy is probably based on [Noether’s theorem](https://en.wikipedia.org/wiki/Noether%27s_theorem), which tells us that any symmetry has an associated conservation law. In this case, it is the symmetry of time translation which has the associated property we call energy which is conserved. By time translation symmetry I basically mean that you get the same result if you do the same thing at different times.
This doesn’t really say what energy is, though, it just says that it’s a property which has a certain property…
In short — energy is a property of a physical system, which is conserved*. There is no substance to the energy that we know of. We can, however, calculate how much energy a system has and we expect this amount to be constant.
According to the Noether Theorem the conservation of energy is really just a consequence of the fact, that the laws of physics don’t change with time. I.e. you could make the same physical experiment the day before or the day after and it would give the same results. To show how, however, one has to understand Lagrange’s physics, which is outside the ELI5
*) in fact the expansion of the Universe doesn’t conserve energy in the large scale (which is consistent with Noether Theorem as the Universe in large scale does change with time)
Energy isn’t really a tangible “thing” at all. It’s essentially a measurement of a thing’s ability to do work. You can think of it as “measurable capacity to do work”.
>What IS energy tho?
In some cases, the only way to see, in the physical world, how much energy something has, is to measure how far away it is from other objects.
For example, we talk about [gravitational potential energy](https://en.wikipedia.org/wiki/Gravitational_energy); two bodies have gravitational potential energy if they are far apart.
* A mass of water has gravitational potential energy because of how the force of gravity is trying to pull it towards the center of the earth’s mass.
* The farther it is from the center of mass, the more energy it has; and we can use this energy to do work; that’s how a [water wheel](https://en.wikipedia.org/wiki/Water_wheel), or a hydroelectric plant.
But gravity isn’t the only force of attraction. Electromagnetic attraction is possible too. In fact, electromagnetic attraction is the force that governs chemical reactions, and all the chemical bonds that hold objects together. So what does an electromagnetic version of potential energy look like?
A rubber band has what we call [elastic energy](https://en.wikipedia.org/wiki/Elastic_energy). We can think of elastic energy as a form of distance too: it exists when we stretch the ends of the rubber band a farther distance from one another, than they would ordinarily be.
Ultimately, elastic energy exists because of elasticity, a property where the particles that make up an object try to return themselves into a certain shape. When we stretch those particles out of shape, the energy is embedded in the distances of how far away they each are from their ideal position.
So we could say that energy is the potential for one of the fundamental forces of nature, to move an object across a distance. This fits with how, mathematically, energy is force times distance.
Energy is more of a measurable property than a physical thing. Like speed. You can’t put speed in a cup, but you can measure how much speed something has.
Depends what terms you’re thinking. For example in electrical terms, power (watts) x time (hours) = energy (watt-hours or kWh)
Energy is the potential to do something useful.
Cars and bullets use kinetic energy.
Dropping something = potential energy.
Most engines and power plants use chemical energy. Etc.
For humans, energy is an abstract denotation of “how much work can be done”. And by ‘work’, it usually means ‘change’.
The change can be “change in speed over time” and the energy be measured in HorsePower (how much weight can be moved in one second).
It can be a measure of how much change in temperature, the energy in this case can be measure in Calories or Joules (how many degress can be transferred per one gram).
Kinectic energy is basically how much ‘potential’ a moving object has to transfer the velocity to another object. A moving truck has “more energy” so it can apply its energy to change – let’s say, the position of a tree more easily than a moving bicycle does. Or a hot stove can change the temperature of the water more than your warm hand does.
Simply put, energy is the ability to effect change. There are a lot of ways that manifests, and a lot of complicated descriptions for how it works, but it isn’t a thing, any more than knowledge is a thing.
When an object moves, that movement is energy. When that object hits another object, it will transfer some of that energy to the other object, and change how it moves. There may also be sound (other movement), heat (molecules within things moving faster), and light (which deserves its own ELI, as things moving as fast as light does start to have weird interactions with time).
When you put clothes in the dryer, and they come out stuck together, and they crackle a bit when you pull them off, it’s because some clothes have transferred electrons to other clothes, resulting in electricity, which is energy related to the movement of electrons.
Just as motion isn’t a thing you can touch, so is energy not a thing you can touch. Rather, it’s a measurement of how much one thing can change other things.
>Like, i know it’s the ability to do work and all that, but this isn’t what energy is, it’s what energy does.
No, it’s definitely what it **is.**
If it helps, think of it as if it were mana in video games. Everything has it, and to do anything requires spending mana. Just imagine any action or process that a system can perform is a spell that consumes mana. And to get more of it, it needs to be recharged by taking the mana of something else.
All matter around us is made up of massive atoms. The mass of a body represents its internal energy, which is expressed by the famous expression E = mc² discovered by Albert Einstein (c being the speed of light).
Might be dumb but, WHY is energy there? Can’t two atoms interacting, just go and collide with each other rather than interacting with their energy shells?
At its most basic level energy is the capacity to cause motion.
Chemical energy can move your car. Thermal energy is the kinetic energy of the molecules in an object. Gravitational energy is when something moves towards another massive object.
There are deeper explanations, but if you aren’t going to learn calculus you should probably ignore them. Somebody without a very strong math background isn’t going to comprehend Noether and symmetries.
All these scientific observations and experiments require words, the mind, and sense organs to explain what they do from the perspective of humans. The thing is, humans are using tools that are limited in their capacity to know what things are. It’s not their nature to know. We can talk about what they do, how they look, but not what they are. This is just the nature of these tools.
#Not ELI5, but…
Like you said… it’s a quantity describing how much work a system is capable of producing. Work is a “rate” quantity defined as an amount of energy being used up per second. That’s black and white definitions of things.
In practice you care about the “work” quantity a lot more often because you are usually trying to design something that can output “energy” *at a specific rate.*
Energy, then, **is just a quantitative property that can describe the state of an object or system.** A red hot piece of iron has high (thermal) energy State. A bullet speeding through the air has high (kinetic) energy state. An anvil sitting atop a 500-meter tall cliff has a high (gravitational potential) energy state.
If that anvil gets kicked off the cliff it will begin LOSING (potential) energy while instantly GAINING that exact amount of energy in another form (kinetic AND thermal due to air drag). This re-balancing of energy will continue until the anvil hits the lowest ground it can reach (or hits a coyote), at which point it is said to have 0 potential energy. The instant before impact, the anvil would have maximum kinetic energy and minimum potential, as it reaches top speed before a quick stop.
The re-balancing is known as “conservation of energy” and follows what we observe in real life. Energy is always conserved. The anvil started with a high state of potential energy and it ends with a high state of potential energy, even if we can’t see it. The air drag heated up the anvil slightly during its travel. Sound waves were emitted as the anvil falls through the medium of air. All the potential energy was replaced by kinetic during free-fall. Once it has landed, gravity still acts on it. If we could create a new deeper cliff, the anvil would fall some more. What this means is that **in the long term, objects and systems tend to exist in discrete states of energy.** The anvil can EITHER be on the cliff OR at ground level. So there are two possible energy states for that system.
It should be no surprise that the physics of electromagnetism are very similar. 12V car battery has a 12V “potential difference.” That means a single electric charge within the battery “feels” 12V of “force” pulling it towards the direction of opposite charge. This is analogous to how the anvil “feels” the potential energy of gravity pulling it off the cliff from high energy to lower energy. It’s pure luck, our previous understanding, and the beauty of nature to thank for this striking resemblance between Newtonian mechanics and electromagnetism.
It might help to imagine energy as a “system property” where you are given a bar graph of the various types of energy we know of like grav potential, kinetic, thermal, acoustic, electric potential, etc. When the system is dormant, everything is FIXED and the bars each show a different value. When we force the system to accept or perform work… aka the system undergoes an event…the energy levels will change by type. At the end of the event, the system will have the EXACT SAME amount of energy, just distributed to the categories a bit differently.
Now, you might think giving off heat and sound would be a net energy loss, thus breaking the rules. That just means you haven’t properly considered the system at hand, which includes the atmosphere that the sound and heat has dissolved into. When the “system” is properly selected, we can take advantage of the “conservation rule” and know for a fact that the net CHANGE in energy will be 0. This can help us safely assume things we otherwise couldn’t measure or know about.
In practical matters, if you know the mass of a bullet as well as the mass AND speed of the gun’s recoil. You could determine the bullet speed as it leaves the barrel. This is one example where energy methods can help out a lot with something that would be tough to measure or calculate.
energy is kind of counterintuitive because it is less something that makes things happen and more a way to describe what is happening.
So we see an object move from a to b, we say „the object apparently had more energy in place a, so it moved to place b to reduce the energy“ Now what this means is basically „seems like the object had a reason to move, so it moved.“ it‘s as general as possible.
like when something falls down. It used to be high, it wasn‘t lying ontop of anything, so it fell to the ground. The reason, as we know, is gravity. But maybe if we don‘t know the reason or if the reason is too complicated and unimportant, we might want to just say „there was pontential to move, and then it moved“.
It sounds weird when you describe everyday phenomena like that but basically everything has an energy level that is influenced by everything around it.
You have a child, the child has two friends and he wants to visit one of them. Friend 1 has an annoying little brother while friend 2 has strict parents who don‘t let their kids watch tv. Say, for the kid the annoying brother is worse than a lack of tv. So based on this, we can give the houses an inherent attractiveness score. The home has a low level of attractiveness, house 1 has a higher score but house 2 has the highest score (energy is inverted for math reasons, so high score means low energy). we can play with that by giving family 1 candy for the kids or buying an x-box for the home. This alters the scores but it‘s always low score => high score.
The attractiveness score isn‘t necessarily something physical but it definitely exists as a property of the houses. Our child has desires and free will, but technically we don‘t have to know that to determine the attractiveness score. we just have to watch the child long enough and figure out all relevant parameters. And this is how we determine the energy levels of things in relation to other things. Molecules might not have a conscious desire to move and bind and split, but they do so all the same. And we can give each possible state an energy level, that reflects how it‘s gonna behave and then we can do a whole lot of math with that.
Energy is a bit hard to define.
For example: in hot air, the “energy” it has when you warm it is the average kinetic energy of its atoms increasing. So in that case its kinetic.
A photon has energy – but its a different thing than the kinetic energy carried on the speed of an atom.
Potential energy is converted to kinetic and vice versa, but its different things.
The energy available in an unbroken uranium 235 atom is something else entirely, but then it converts to stuff moving very fast and radiation.
I’d say that its a value that aggregates several different things giving some equivalences
Energy is ultimately just a human concept. It is not a true physical property. In science its like the ability for something to do damage or do work. Fast moving things have more energy than stationary things, combustible things have lots of energy to release, heavy things that can fall have more potential energy than lighter things because they can do more damage.
Here’s a slightly mind blowing follow up question: what’s the origin of mass? You’ll find it surprising that somehow mass and energy are deeply related.
> i know it’s the ability to do work and all that, but this isn’t what energy is, it’s what energy does.
That’s not true. The ability to do something isn’t the action itself.
When a system has energy, that energy can be used to do lots of things; pushing something, shining a light, heating something up. But before the energy is converted, it isn’t any of those things; it’s the property of the system that allows it to do those things.
So the way understand it, it is simply a property of matter that we have discovered. Other measurements like length, mass, volume, etc., make intuitive sense to us because we can directly observe them. We can measure the length of the object by stacking several smaller objects with the same length for example (where these smaller objects function as the units). But measuring energy is not so obvious, and it took numerous experiments to figure out that a value like that “exists”, namely that it makes sense to use it
The energy held in something is its mass times the speed of light squared
That energy may be expressed in a myriad of ways.
Energy cannot be created or destroyed…..only changed.
That’s all I know, thanks for coming to my Ted talk.
I dont like these answers so I will offer my own, which is more philosophical but still accurate.
Energy is potential to change a system. All energy can be thought about as potential energy. What energy *is* is a measure of how much change can be imparted from within a system to outside that system.
At its most fundamental level, energy is the potential to actuate change.
It’s like money, but a value store of work. You can save it (potential energy) you can use it (kinetic), you can borrow but can’t really go negative in the absolute sense. It’s fake like money as a construct but at the same time feels real through everyday experiences.
It’s not really anything. It’s kind of like asking what a dollar is. You can think of it as a piece of paper with a picture of George Washington on the from and an eagle and a pyramid on the back, but then what happens if you exchange ten of those for a picture of Alexander Hamilton and the U.S. Treasury Building on the back? It’s, like, a tenth of one of those pieces of paper, but in some abstract way; you can’t just cut off the part that’s a dollar. Originally there was some silver or gold in a vault somewhere, and the paper was acting like a claim check, but now it’s a claim check for nothing in particular, except the abstract notion of a dollar. And then you have things like bank accounts and debts — you can have *negative* dollars somehow! — so it’s just entirely abstract. It’s just a kind of accounting trick.
And that’s more or less what energy is: a kind of accounting trick to help sort out what’s happening in some physics problem.
It’s not like it’s even some intrinsic property of a thing. Think about this: a one kilogram ball thrown at ten meters per second as 50 Joules of kinetic energy (m v^2 / 2), but in another frame of reference, maybe the ball is traveling at 20 m/s, so it has 200 Joules of kinetic energy, and in another it’s at rest, and has zero Joules of kinetic energy. Similarly, potential energy depends on what you might fall towards — the ground? the center of the earth? the sun? the black hole at the center of the Milky Way? Or are we just talking about negative potential energy with respect to some point far away in intergalactic space?
You can’t look at some object and say, “this is how much energy this has”. So really all it is, fundamentally, is a thing you can use to do some kind of accounting to help solve physics problems.
That’s true of most things in physics.
I’ve often wondered what energy is as well. On a fundamental level. I never took advanced classes in HS and college was out of reach so I’m really clueless.
But I think about energy coming from the sun, and being absorbed by a plant, which uses that energy to grow bigger. Then we cut that plant and consume it and the energy stored in it is transferred to us. Then that energy is used to do work like walking or lifting an object. But then where does the energy go from there? If I slide a cup across my table, I put some of that energy into overcoming the friction of the cup and the table, but where does the energy go from there? Is it lost?
All of this thought process could be completely wrong. I have no clue. It’s just what I think about during a 12 hour shift doing meaningless manual labor.