Q&A for How to Understand E=mc2

Einstein is basically saying that mass and energy are different forms or descriptions of the same thing. By converting mass to energy, you are still conserving the mass through the form of energy.

Mass and volume are not the same. You can stretch or compact an object to change its volume, but the amount of matter inside it will stay the same. In the ice cube example, the molecules in liquid water are closer together, but they're still the same molecules that were in the ice.

No, not even close. Keep in mind that the speed of light is 3.00×10^8 meters/second. For us to even go a fraction of that speed, 1% for example, we would have to go 3.0×10^6 meters/second which is approximately 1,864.1 miles/second or 6,710,808.88 miles/hour. We are not even close to that speed yet technologically.

Uranium and other radioactive elements are very unstable and therefore are the easiest elements to split (not that this is easy!). The difficulty lies in finding out how to split the more freely found elements since they are not so inherently unstable in the first place.

No, the article was saying that mass and energy are interchangeable because as you increase one, the other has to be increased due to the equation to balance it out.

Atoms are the building blocks of matter, and they only consist of a certain amount of subatomic particles. They are considered "small" perhaps, since we are so large in comparison, and they are one of the smallest units of creation.

There's no such thing as absolute time. Two people moving at different relative speeds can disagree on how much time has passed between two events. However, if you could send a signal faster than light, things get weirder: the two people could disagree over which event came first. This leads to "time travel" paradoxes, such as sending a message to yourself in the past. Most physicists think faster than light signals are impossible, partly for this reason.

Special relativity explains that accelerating an object with mass takes more and more energy as the speed increases. When you're near the speed of light, this effect is so noticeable that you can only edge closer and closer to light speed, no matter how much energy you put in.

F=ma and E=mc2 are both encompassed, surpassed, and related by this most fundamental law/truth in all of physics: Inertial resistance is proportional to gravitational force/energy. (Gravity has energy.) This law applies to the Sun and to photons, and it applies to black holes. Balancing gravity and inertia is what is most fundamental and important here. So, force/energy, acceleration, photons/light, gravity and inertia, and larger and smaller space are central considerations for what is impacted by this equation.

Almost all of the mass in an atom is located in the nucleus, where protons and neutrons are bound together very tightly. Nuclear fission breaks apart these tight bonds and converts some of the nucleus mass into energy.

Physics terms refer to precisely defined, physical phenomena. Burning wood transforms matter into energy, but most religions would not call the result a soul. Einstein himself and many people since have interpreted his theories from a religious perspective, but that's outside the scope of the equations themselves.

Mass is nothing but the ratio of volume and area. The area of water is more than that of the ice cube and the volume has also changed. As a result, the mass will stay constant.

I would focus on the idea that energy (for instance light and sound) and mass (and physical object) can be converted to each other. The "c squared" part is more difficult to explain, but you could talk about how Einstein figured out that c (the speed of light) is the "speed limit" in the universe.

Only c is squared. In the equation, E=mc^2, the square only ever refers to the variable or value to its left. For m and c to be squared, it would have to look like this: E=(mc)^2

Light is a form of energy! Heat doesn't have mass, either, yet the breaking of bonds between atoms (which have mass) can produce heat. Other chemical reactions release energy as light, and photosynthesis involves the transformation of light energy into stores of chemical energy (which have mass). For a more fundamental explanation of how "light" relates to E=MC^2, do not consider "light" as part of the equation. As the article says, C^2 functions as more of a conversion factor (meters squared per seconds squared) rather than anything having to do with photons in particular.

The speed of an object has no correlation to its ability to "pass through" another object. Consider this, if you run faster than another person at a wall, you still approach the same matter. The only difference is that greater kinetic energy is being transferred to the wall between you and wall than the other person. That is why it hurts more to collide with a wall at a faster speed. Likewise, if the wall cannot exert the same force on you back to you that you exerted, which makes it hurt, then the wall collapses. Light moves at the speed of light, but does not pass through walls, since you cannot phase through matter with a change in speed.

To consume 100% energy of a matter would be to destroy it completely. Matter can only change form, not be completely destroyed. If you could destroy matter 100% then, in theory you could destroy energy 100%. That doesn't sound like a good idea.

In the equation of speed as distance over time, time doesn't affect distance, but distance affects how much time exists. The counting of time does not speed up or slow down. The constant speed of light refers to the speed light waves travel at; the time it takes for a light particle to travel is unrelated to the speed of light.

Squaring is multiplying a number by itself. For instance, 2 squared (2x2) is 4. In this formula, you would multiply c by itself, and multiply the result by m.

No, thermal energy will only cause thermal expansion where the volume increases in response to a change in temperature. If you have the same amount of the substance even after a temperature change, the mass will stay the same as stated by the law of conservation of mass/energy (mass or energy cannot be created nor destroyed), but the volume will increase. The density will change however since density is a ratio of mass to volume. If you increase the volume and then divide the mass by the volume, the density will decrease. The point is, regardless of temperature change, as long as the amount of that substance is consistent, mass will be the same. Make sure you don't mix up density and mass.

no. Only the observed speed is limited. If you observe something traveling faster than the speed of light, you will only observe that object moving at the speed of light, even though it is moving faster.

C refers to mathematical constant for the speed of light, and c square is used because the constant is squared.

It transforms into other forms of energy. For example, the explosion of bomb is a combination of multiple transformations (chemical energy --> heat energy --> light energy + sound energy).

C is the constant, and it is being squared to keep all the units congruent as energy is measured in joules (kg squared). Squaring C ensures that the relationship between energy and mass is dimensionally consistent.

Light doesn't really have temperature, rather it can transfer energy onto an absorbent surface (one with low albedo), which then increases the kinetic energy of the molecules on that surface. This means they vibrate faster and this motion turns some of the energy into heat energy, which we perceive as the temp. But you need a medium of matter to do this; light in a vacuum has no temperature, though can change the temp of objects that it comes in contact with.

Light does not require a medium to propagate. It is a non-mechanical wave, unlike sound.

In nuclear plants, the equation can be used to decide how much substance is needed to generate a certain amount of energy, and in case of a nuclear disaster, to determine how much damage will be caused before the matter is used up. In astronomy, the equation is used to determine what density the universe has.

The speed of light is 299,792,458 m / s (meters per second). So apply that to the formula multiplying m (mass) to c (299,792,458) ^ 2 to get E.

If you mean t as time (in seconds), it can be solved by t = ±√((m*s^2)/E), where t is time, m is mass, s is distance (or displacement) and E is energy. You can get the t from equation of velocity (v = s/t), where speed of light c is equal to velocity v.

Yes, not to be confused with weight which is measured in Newtons. Mass is derived from volume and density. An object on the moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that determines the strength of this force.