
#1
May1709, 09:02 AM

P: 2

Hi all,
If I have an object with zero mass in a vacume and apply say 1n of force to the object how can I calculate its acceleration, and current speed at any time? Thanks all. 



#3
May1709, 09:16 AM

P: 2,453

all massless particles travel at the speed of light.




#4
May1709, 09:30 AM

P: 662

How do I calculate acceleration with a mass of Zero
As Vanadium50 pointed out, a = F/m gets you in trouble. You can understand this more clearly by considering what happens if you apply this same force to a succession of increasingly smaller masses. Look at the curve of a = F/m (a hyperbola), and you see that the lighter the mass, the higher the acceleration, which goes to infinity as the mass goes to zero.
That's the nonrelativistic answer, i.e. what Newton would have told you. Cragar's response comes from Einstein's Theory of Relativity, where there are no infinite speeds (or accelerations). The speed of light is the absolute speed limit, so massless particles must all move at that speed (they can't ever be at rest, or they would appear to be moving at a speed less than c to some observers). 



#5
May1709, 07:28 PM

P: 2

Basically I need a way of working out the following scenrio. An object with a mass of say 10kg is sat in geo stationary orbit. The object has a way to reduce it's mass to zero. It applies some thrust say 1n for 1 second It then returns to normal mass How far has it traveled? 



#6
May1709, 07:53 PM

P: 2,050

(How were you going to push so hard against something that doesn't resist being pushed against, anyway?) 



#7
May1709, 07:59 PM

PF Gold
P: 7,125





#8
May1709, 08:23 PM

Mentor
P: 22,000




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