Imagine a rocketship that leaves our solar system and accelerates, directly away from the sun, to 1/3 c relative to the sun.

It's second stage separates and accelerates directly away from the sun to 1/3 c relative to the first stage.

It's third stage separates and accelerates directly away from the sun to 1/3 c relative to the second stage.

How fast, relative to Sol, is the third stage travelling at the end of it's acceleration?

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I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that.

I am human. Fully human.

Depends on who made the Rocketship.

If it was Ford, the alternator would have blown out past the second stage and the tail lights wouldn't work.

If it was Chrysler, the transmission would have gone out when shifting from 1/3 to 2/3 gear.

if it was Honda, it would never pass the speed limit. But you can blame this one on the driver and the ship will never break down.

:P

Do your nasty math yourself!



By the way, just to WAG it, about .9c

Yeah, these datgummed lazy whippersnappers always asking us their homework questions...

Seven-ninths of light-speed, according to the relativistic addition of velocities.

Grant Hutchison

Seven-ninths? That sounds like an improbable figure... Well, I'll be darned. That's correct!

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Everyone is entitled to his own opinion, but not his own facts.

AAANNNTTT! Acceleration is absolute. You are describing a circumstance that has no meaning.

The circumstance absolutely has meaning, and the answer is 7/9, as said before.

You really shouldn't be asking us about your homework problems though mugs

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The problem is stated in terms of relative velocities, and is quite meaningful. But observers scattered across the different inertial frames referenced in the problem will observe different accelerations, too.

Grant Hutchison

In defense of the automakers...

At least refurbished Ford alternators are a dime a dozen at any Pep Boys, NAPA, or other Auto Parts store, and if the light goes out, it's a $12 bulb, rather than a $130 tail light assembley (thanks, Honda...)

True, but the good thing about Chrysler transmissions is that the forward gearing is separated from reverse, so if that happened, you could simply flip 180 degrees and keep on going. You'll need a rearview mirror, though...

I've owned two Hondas and am on my third Ford. To date, each of my Hondas has had more breakdowns than any one of my Fords, and aside from my current Ford, I owned each of my cars for roughly the same period of time and milage.

Come to think of it, total cost for parts and repairs on all my Fords comes to less than $300, but for my two Hondas, it came to more than $3,000.

Hmmm...

And I babied my Hondas, but drove my Fords into the ground.

__________________
I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that.

I am human. Fully human.

cjl, Neverfly, I confess - I gave myself a homework problem, then was too lazy to look it up myself.

Shame on me!

Actually, we've seen dozens of related questions over the last six months, and instead of tackling it each and every time, I hit upon this simple, straightforward scenario to highlight how 1/3c +1/3c + 1/3c <> c, from the relativistic point of view.

Thanks, Cougar, for sharing the link to that website - good resource!

__________________
I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that.

I am human. Fully human.