# Real life elastic collision and variation of kinetic energy

• velvetmist
In summary, to determine if a collision is elastic, the change in kinetic energy (delta T) should be small enough to be negligible for the specific application. A common criteria is to have a percentage of delta T less than 10% of the initial kinetic energy (Ti), but this may vary depending on the desired precision and tolerance for error. Keep in mind that a perfectly elastic collision is only an approximation and there is no set standard for determining the accuracy of the approximation.
velvetmist
How small should ##\Delta T## be in a collision to be considered elastic? In elastic collisions ##\Delta T =0##, but as far as I know, just atomic collisions are considered perfectly elastic. Then, which criterias are used to considere a collision between two objects elastic?

It should be small enough that you don't care about the error from ignoring it for whatever your application is.

velvetmist
Ibix said:
It should be small enough that you don't care about the error from ignoring it for whatever your application is.
I don't have any specific application. I was thinking in taking the percentage of ##\Delta T## from ##T_i##, and if it's ##<10\%## it's acceptable, but I'm not sure if it could be a valid criteria.

If you can tolerate an error of 10% in your energy measure, sure.

A purely elastic collision is an approximation to reality. There's no single answer to "how good does an approximation have to be to be useful" - it depends on how big the error is and how precise an answer you need.

velvetmist

## 1. What is an elastic collision?

An elastic collision is a type of collision in which kinetic energy is conserved. This means that the total kinetic energy of the system before and after the collision remains the same.

## 2. What factors affect the variation of kinetic energy in an elastic collision?

The variation of kinetic energy in an elastic collision is affected by the masses and velocities of the objects involved. The total kinetic energy will increase if the objects have different masses or if one object is moving faster than the other.

## 3. How does the angle of collision affect the kinetic energy in an elastic collision?

The angle of collision does not affect the kinetic energy in an elastic collision. As long as the collision is elastic, the total kinetic energy will remain constant regardless of the angle at which the objects collide.

## 4. Can the kinetic energy in an elastic collision ever be greater than the initial kinetic energy?

No, the kinetic energy in an elastic collision can never be greater than the initial kinetic energy. This is because elastic collisions are characterized by the conservation of kinetic energy, meaning that the total kinetic energy cannot increase or decrease during the collision.

## 5. How does a perfectly elastic collision differ from an inelastic collision?

In a perfectly elastic collision, the total kinetic energy is conserved, while in an inelastic collision, some kinetic energy is lost in the form of heat, sound, or deformation. This means that the total kinetic energy after an inelastic collision will be less than the initial kinetic energy.

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