“Almost every way we make electricity today, except for the emerging renewables and nuclear, puts out CO2. And so, what we’re going to have to do at a global scale, is create a new system. And so, we need energy miracles.” –Bill Gates
Energy is one of the most important topics facing our modern, industrialized civilization. What sources we get it from, what we use it for, and how we deal with the waste from its production are paramount to the future of our species on Earth.
Yet in many ways, energy is one of the most poorly understood quantities in all of physics. To help you better understand it, let’s take a look at five good questions about energy. Starting with…
1.) What is energy? Anyone who’s ever taught or taken a course in introductory physics has likely encountered this question. Most physicists, perhaps unfortunately, define energy as the ability to do work. And so you go and ask what work is, and you get the circular definition that it’s the transfer of energy from one source to another.
Maddening.
It’s not like wikipedia does any better, mind you. But just because we don’t have a good definition of it doesn’t mean we can’t quantify, test, and indirectly measure it.
Don’t feel bad; no less a physicist than Newton had no concept of energy. And yet unlike Newton, I bet that you know it when you see it. Some things we do know about energy are:
we know that all mass and matter contains it,
we know how to quantify it,
we know how much is stored electrically, chemically, thermally, sonically, etc.,
we know how to convert it from one form to another,
we know how to use it to accomplish things (i.e., to do work),
we think it can never be created nor destroyed,
and we can generate, calculate, and measure its various forms.
So let’s take on a more useful question than asking for a simple dictionary definition:
2.) What can we do with energy? Well, we already said, “work,” but that has a specific meaning to a physicist. If you “push” something, or otherwise apply a force to it, while it simultaneously moves in that direction, congratulations! That’s what work is!
Whether you’re lifting a weight up, pedaling a bicycle, driving a car, or spinning a turbine, work is being done. And that’s what energy can do.
More than that, of course, is that you don’t need to do it. Anything that lifts a weight, pedals a bike, drives a car, or spins a turbine can do work, and therefore, has energy. Atomic nuclei, molecular bonds, gravitation, relative motion of massive bodies and electromagnetism are all possible physical sources of energy, as nuclear power, fossil fuels, hydroelectric dams, wind power and solar power are respective examples of each.
3.) How much energy do we use? If you’re reading this, you’re probably in a location that has seemingly endless, cheap access to at least one of these forms of energy. Well, all total, humans use a lot of energy. In practice, it’s much easier to measure power, or the rate at which we use energy. So take that power and multiply it by a certain amount of time, and you’ll find out how much energy we use.
How much power do we use?
4.) What’s the “holy grail” of energy? Well, you have to be careful here. Some people dream about taking all the ambient thermal energy around us and using it to meet our energy needs.
5.) What does the future hold for nuclear fusion? Well, we definitely don’t want to do it the same way the Sun does it. But we still want to start with our cheap, light, easy fuel and get that nuclear energy out of it. And we’ve got three ways we know of to make it happen, each one getting closer to the magical (metaphorically) breakeven point. What are th
Source by: http://scienceblogs.com/startswithabang/2011/07/20/energy-five-good-questions/
Energy is one of the most important topics facing our modern, industrialized civilization. What sources we get it from, what we use it for, and how we deal with the waste from its production are paramount to the future of our species on Earth.
Yet in many ways, energy is one of the most poorly understood quantities in all of physics. To help you better understand it, let’s take a look at five good questions about energy. Starting with…
1.) What is energy? Anyone who’s ever taught or taken a course in introductory physics has likely encountered this question. Most physicists, perhaps unfortunately, define energy as the ability to do work. And so you go and ask what work is, and you get the circular definition that it’s the transfer of energy from one source to another.
Maddening.
It’s not like wikipedia does any better, mind you. But just because we don’t have a good definition of it doesn’t mean we can’t quantify, test, and indirectly measure it.
Don’t feel bad; no less a physicist than Newton had no concept of energy. And yet unlike Newton, I bet that you know it when you see it. Some things we do know about energy are:
we know that all mass and matter contains it,
we know how to quantify it,
we know how much is stored electrically, chemically, thermally, sonically, etc.,
we know how to convert it from one form to another,
we know how to use it to accomplish things (i.e., to do work),
we think it can never be created nor destroyed,
and we can generate, calculate, and measure its various forms.
So let’s take on a more useful question than asking for a simple dictionary definition:
2.) What can we do with energy? Well, we already said, “work,” but that has a specific meaning to a physicist. If you “push” something, or otherwise apply a force to it, while it simultaneously moves in that direction, congratulations! That’s what work is!
Whether you’re lifting a weight up, pedaling a bicycle, driving a car, or spinning a turbine, work is being done. And that’s what energy can do.
More than that, of course, is that you don’t need to do it. Anything that lifts a weight, pedals a bike, drives a car, or spins a turbine can do work, and therefore, has energy. Atomic nuclei, molecular bonds, gravitation, relative motion of massive bodies and electromagnetism are all possible physical sources of energy, as nuclear power, fossil fuels, hydroelectric dams, wind power and solar power are respective examples of each.
3.) How much energy do we use? If you’re reading this, you’re probably in a location that has seemingly endless, cheap access to at least one of these forms of energy. Well, all total, humans use a lot of energy. In practice, it’s much easier to measure power, or the rate at which we use energy. So take that power and multiply it by a certain amount of time, and you’ll find out how much energy we use.
How much power do we use?
4.) What’s the “holy grail” of energy? Well, you have to be careful here. Some people dream about taking all the ambient thermal energy around us and using it to meet our energy needs.
5.) What does the future hold for nuclear fusion? Well, we definitely don’t want to do it the same way the Sun does it. But we still want to start with our cheap, light, easy fuel and get that nuclear energy out of it. And we’ve got three ways we know of to make it happen, each one getting closer to the magical (metaphorically) breakeven point. What are th
Source by: http://scienceblogs.com/startswithabang/2011/07/20/energy-five-good-questions/
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