# Applying Einstein velocity addition | Special relativity | Physics | Khan Academy | Summary and Q&A

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January 30, 2016
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Applying Einstein velocity addition | Special relativity | Physics | Khan Academy

## TL;DR

Einstein's velocity addition formula allows for accurate calculations of relative velocities in special relativity.

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### Q: How does the Einstein velocity addition formula differ from Newtonian methods of calculating relative velocities?

In a Newtonian world, relative velocities are simply added together, which can lead to violations of the laws of the universe. The Einstein velocity addition formula takes into account the absolute speed of light, ensuring that it is not violated.

### Q: Why is it important to consider the speed of light when calculating relative velocities?

The speed of light is a fundamental constant in the universe, and according to the principles of special relativity, nothing can travel faster than it. By incorporating the speed of light into the calculations, the Einstein velocity addition formula ensures that this principle is upheld.

### Q: How does the Einstein velocity addition formula prevent violations of the laws of the universe?

The formula includes a denominator that accounts for the absolute speed of light. By dividing the numerator by this value, the result is a value that is always less than the speed of light, preventing violations of its absolute nature.

### Q: How can the Einstein velocity addition formula be applied practically?

The formula allows for accurate calculations of relative velocities in scenarios where objects are moving at speeds close to the speed of light. This can have practical applications in fields like astrophysics an space travel, where understanding relative velocities is crucial.

## Summary & Key Takeaways

• The video explains Einstein's velocity addition formula, which is used to calculate relative velocities in special relativity.

• In a Newtonian world, velocities would be simply added together, but this violates the laws of the universe.

• With the Einstein velocity addition formula, velocities are calculated using a formula that takes into account the absolute speed of light, ensuring that it is not violated.