- #1

Stephanus

- 1,316

- 104

I have a problem concerning the unit of acceleration.

All this time in Relativity, we have been talking about c.

Either as a distance unit (light travel for 1 second) or as speed.

Sometimes we describe it as 300,000. Sometimes as 300,000,000 or 186,000.

The time unit is always second. No matter if you use English or metric

But this number is well understood.

It just hits me.

"The speed of light is 100,000,000 arm distance divided by swing time"

Supposed that their 1 arm distance is 0.5 meter

and their (pendulum) swing time is ... ##\frac{1}{6} (our) seconds## of course.

But acceleration is distance/(time *

**time**). I'm having trouble with this term.

1. An object travels at 0.6c.

This I can understand perfectly well

2. The length is 2c.

This is 600,000 km.

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3 It accelerates at 0.5c

Now this is problem. I can't picture what is the acceleration?

-----------------------------------------------------------------And instead of asking question number 3. I'd like to ask about this question.

Two observers (A and B) are at rest.

Then B accelerates at 30,000km/sec

^{2}for 100 seconds then stops accelerating. But it still travels steadily at

Question:

What is B speed wrt A according to velocity addition formula?

##s = \frac{u+v}{1+uv}## Remember u and v always in c unit.