# Non-relativistic deflection

by bobie
Tags: deflection, nonrelativistic
PF Gold
P: 636
 Quote by Nugatory Look at the series expansions. you can approximate either function to just ##x## .
Thanks Nugatory,
I am trying to understand the rationale of the formula, in the first place:

the ray is moving tangentially at 3*1010 cm/s
it gets a normal velocity 127 700 cm/s , right?

when we divide v/c = 127 700/3*1010 = tanθ = 0.000004256 we are dividing the legs of a rectangle and we get tan θ, which should be the angle of deflection, right?

Why do you need to approximate the tangent to the angle or to its sine,
why don't you simply do tan-1 θ ?
 Quote by Mr-R Since in this quasi-Newtonian mumbo jumbo we considered the photons to be some sort of capsules that has mass. Then it has a variable velocity.
Is that really so? it doesn't make sense, apparently, as the pull is perpendicular to the motion
P: 482
 Quote by bobie the pull is perpendicular to the motion
In the usual hyperbolic path of deflected light there is only a single point where the pull is perpendicular to the motion.
PF Gold
P: 636
 Quote by DrStupid In the usual hyperbolic path of deflected light there is only a single point where the pull is perpendicular to the motion.
All along the path there is a longitudinal pull which produces blue/red -shift and the normal pull that produces deflection. Neither force influences velocity. right? If so isn't it weird to say that that the photon/wave/ray has variable velocity?

The point is anyway the angle, if we know its tangent v/c = tanθ, why aproximate it to the angle and not simply derive tan-1?
And, again, as we are considering non relativistic deflection, what happens when we apply to the earth, deflected by the sun?