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fornax
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Homework Statement
A proton is moving along the main axis of a uniformly charged thin ring. The charge density on the ring is 5.0nC/cm and the ring radius is 1.0cm. Initially the proton is 2.0cm (along the axis) from the center of the ring with the velocity towards the center of the ring. What initial speed should the proton have such it will cross the plane of the ring?
Homework Equations
ΔU = ΔV*q
ΔKE + ΔU = 0
Vcenter = KQ/R
W = -ΔU
The Attempt at a Solution
50nC/cm = 500nC/m
Vcenter = KQ/R
V = ((9x10^9)*(500x10^-9))/.01^2
V = 4.5x10^7
ok, looking at my paper, I then went on to multiply V*d, and I'm not sure why anymore...
I can't seem to find the correct equation for the V on the axis in my notes. I could use V*q for ΔU then user ΔU to ger ΔKE(1/2mv^2) but that gets me velocity if it accelerated toward the ring... ugh.
If I had V at .02m, the I could get ΔV between the center and there, then get ΔU, assume ΔKE is zero at the center, then get the velcoity at .02m with ΔU = ΔKE. Am I reasoning this correctly? Also, mind sharing that formula? :)