Speeding lab experiment

  • Thread starter Pengwuino
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Pengwuino
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Ok this'll probably change my perception on what relativistic kinetic energy is so here goes.

Lets say you have a lab experiment ready to fire a particle at .6c into a wall or something (or maybe even another group of particles). Lets say you fire the entire lab experiment off from an observer at .35c. Now, using relativistic kinetic energy, the particle according to people traveling with the lab experiment will hit the other particles with a certain KE right? Now, what would the KE be relative to the observer whos standing still? It seems like it would be a different KE and deliver more energy to the particles according ot the observer.

I think i might have realized why thats not the case (as i was writing the question!), but i just wanted to ask to make sure i know why im wrong.
 

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  • #2
HallsofIvy
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Before you go saying it would "deliver more energy to the particles according ot the observer." notice that the observer also sees the target particles as moving with speed 0.35c.

Suppose you are driving down the road at 30 mph and crash into a parked car! Heckuvalot of energy transfer!
Suppose you are driving down the road at 60 mph and crash into a parked car.
Heckuvalot more energy transfer!
Suppose you are driving down the road a 60 mph and hit the back of a car doing 30 mph. Which of the above two cases has the same energy transfer (at the time of the hit- ignore what happens when both cars start skidding across the road!)?
 

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