Light's Mass: 0 N = Infinite Acceleration?

[unscientific]

F=ma a = F/m Light's mass: 0 N = infinite acceleration?

 

[JesseM]

F=ma a = F/m Light's mass: 0 N = infinite acceleration?

Why is this on the relativity board? And if 0 N means "0 Newtons", ie F=0, this will mean a=0 for a finite mass, not a=infinity.

 

[DaveC426913]

F=ma a = F/m Light's mass: 0 N = infinite acceleration?

F=ma is Newtonian classical physics. Cannot apply to relativistic concepts.

 

[unscientific]

light has 0 mass, and I am talking about light being 0 mass here, jessem

 

[bernhard.rothenstein]

light has 0 mass, and I am talking about light being 0 mass here, jessem

light has zero rest mass!

 

[JesseM]

light has 0 mass, and I am talking about light being 0 mass here, jessem

But F=ma doesn't apply in relativity, although on this thread masudr mentioned that there is a similar equation relating the force 4-vector to the momentum 4-vector, f_{\mu} = \frac{d}{d\tau}p_{\mu}. Also, you said "0 N", I assumed the N was short for "Newtons", which is a unit of force, not mass.

 

[actionintegral]

This isn't even a physics question! Every sixth grader tries to divide by zero thinking the answer is infinity. This belongs in the homework section.

 

[JesseM]

This isn't even a physics question! Every sixth grader tries to divide by zero thinking the answer is infinity. This belongs in the homework section.

It is true in a sense in calculus, though--the limit of 1/N as N approaches zero is infinity.

 

[therapeuter]

what i have heard is that photon, since it is already flying at the speed of light, cannot be slowed down. so it cannot be going slower than the speed of light and then accelerated to the speed of light. neither can it be accelerated from the speed of light beyond the speed of light. so F = ma has no application to light.