### Subject: Confusion about relativity and mass

Date: Sun Feb 20 22:13:40 2000
Posted by Judson White
City: Rochester State/Province: NY Country: USA
Area of science: Physics
ID: 951106420.Ph
Message:
```
I've read that as an object increases speed, and especially as it
approaches the speed of light, that its mass increases.  After reading a
few books I still have not been able to reason out two things.  One is,
that since there is no standard frame of reference, that if some observer
was going the same speed as some other object that was near the speed of
light (and more importantly, had increased mass) if the observer would
understand this objects weight to be unchanged?

Another similar question I have is that if two objects are moving along at
near the speed of light (say 99%) relative to some frame of reference, it
seems like one object could increase some arbitrary amount of speed
relative to the other (say 2% the speed of light) but still not increase 1%
the speed of light from the other observer's viewpoint... so, what further
confuses me is how an object becomes harder to accelerate (increases in
mass) if it can always be viewed as being at rest from *some* viewpoint,
and therefore not being near the speed of light.

```

Re: Confusion about relativity and mass

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