How Is Kinetic Energy Calculated for a Moving Charge?

AI Thread Summary
The discussion focuses on calculating the kinetic energy of a charged particle released from rest in an electric field. Initially, the electric potential at a distance of 1 m from a fixed charge is 310 V. The user calculates the electric field and attempts to determine the final potential as the particle moves far away from the charge. Ultimately, the solution reveals that the final potential is 0 V, leading to the kinetic energy being calculated as 1.55 J using the formula KE = q(V_initial). The problem is resolved by confirming that the kinetic energy is directly related to the initial potential difference.
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[SOLVED] Kinetic Energy of a Charge

Homework Statement


A charged particle q, which is fixed in position, produces an electric potential of 3.10E2 V at a distance of 1 m away (the potential from q vanishes at infinity). If a particle of charge Q=.00500 C is released from rest at a distance of 7.00 m from q, what will be its kinetic energy after moving very far from q?

Homework Equations


V = Ed
E = Fq
KE = q(V_initial-V_final)

The Attempt at a Solution


Since V_initial is given at 310 V, I need to solve for V_final.

Since V = Ed, I solved for the electric field of Q:

E=kq/d^2

E=(9x10^9)(.005)/7^2
E=10285714.29

Then, since V=Ed
V = 10285714.29.

This is where I get confused because I don't think this is a realistic number since V initial was 3.10E2. Please help. I think all I need to do is find V_final to solve the problem, but I am not doing it right. Am I going about this the correct way?

SOLVED: Nevermind, figured it out.
 
Last edited:
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V_final had to be 0V since it is very far away from q, so the kinetic energy is equal to q(V_initial). KE = (Q)(V_initial) = (.005)(310) = 1.55J
 
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