# Collision question regarding mass loss

• student85
In summary, when two subatomic particles collide at high speeds, they form a bigger particle with a lower mass, causing the mass lost to transform into energy according to Einstein's equation E=mc2. This does not occur with non-subatomic particles, as their rest mass does not change unless they transform into other particles. The concept of relativistic mass, which changes with speed, is not universally accepted and may eventually be replaced with the use of the rest mass in equations.
student85
This might be stupid but I was thinking, when two subatomic particles collide at very high speeds, they form a bigger particle whose mass is less than the sum of the smaller ones, and the mass lost transforms into energy as in Einstein´s equation E=mc2.
What happens with non subatomic particles, say two balls colliding or whatever. Is there a mass loss that turns into energy. THIS SOUNDS VERY OFF LOL, because the amount of energy released with just a little bit of mass is huge. But then, what is wrong here? Why doesn't this happen, or if it does, why isn't it perceived?

student85 said:
This might be stupid but I was thinking, when two subatomic particles collide at very high speeds, they form a bigger particle whose mass is less than the sum of the smaller ones, and the mass lost transforms into energy as in Einstein´s equation E=mc2.
What happens with non subatomic particles, say two balls colliding or whatever. Is there a mass loss that turns into energy. THIS SOUNDS VERY OFF LOL, because the amount of energy released with just a little bit of mass is huge. But then, what is wrong here? Why doesn't this happen, or if it does, why isn't it perceived?
That depends on wether you are talking about the rest mass or the relativistic mass. The rest mass does not change unless the particles transform into other particles. The relativistic mass changes with speed. Not everyone likes the concept of relativistic mass, but it's been around a long time and will probably die a very slow death.

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html#c5

OlderDan, is that your opinion or is it really dying? Why?

I mean the part you said about relativistic mass having a slow death.

student85 said:
OlderDan, is that your opinion or is it really dying? Why?

I mean the part you said about relativistic mass having a slow death.
It is not my area of expertise (come to think of it, I may not have one at all) but I have come across numerous references to the concept of relativistic mass as being unnecessary and not particlularly useful, including the quote from Einstein in the link I posted. It's easy enough to write gamma*m where gamma = 1/sqrt(1-v²/c²) and m is the rest mass when that particular combination appears in the equations instead of always putting the subscript on m_o when rest mass is indicated. But lots of people used m for relativistic mass for a long time, and you still see it in many references. It's just a matter of convention, not some difference in the physics. The energy expressed as E = sqrt[p²c² + (mc²)²] where m is the rest mass is generally more useful than E = mc² where m is the relativistic mass in analyzing relativistic systems.

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## 1. How does the mass of an object change after a collision?

The mass of an object does not change after a collision. According to the law of conservation of mass, the total mass of a closed system remains constant, regardless of any physical or chemical changes that may occur.

## 2. Can an object lose mass during a collision?

Yes, an object can lose mass during a collision. This is known as mass loss and it occurs when some of the mass of the object is converted into other forms of energy, such as heat or sound.

## 3. What factors can affect the amount of mass lost during a collision?

The amount of mass lost during a collision can be affected by the speed and angle of the collision, as well as the materials involved. Inelastic collisions, where the objects stick together after impact, tend to result in more mass loss than elastic collisions, where the objects bounce off each other.

## 4. Is mass loss always a bad thing during a collision?

No, mass loss is not always a bad thing during a collision. In some cases, such as in particle physics experiments, mass loss can be intentional and even desired in order to study the behavior of subatomic particles.

## 5. How is mass loss calculated in a collision?

Mass loss in a collision is typically calculated by measuring the initial and final masses of the objects involved, and then determining the difference between the two. This can be done using a scale or other precise measurement tools.

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