Force on a charge obtained from electric potential

AI Thread Summary
The electric potential along the x-axis is defined as V = 111x^3 - 517x - 258. To find the force on a -444 μC charge at 56.5 cm, the electric field E is calculated as the derivative of V with respect to x, resulting in E = 333x^2 - 517. Evaluating E at x = 0.565 m gives E = -668.7 N/C. The force F is then calculated using F = qE, yielding approximately 0.297 N, but the initial attempt was deemed incorrect. The user seeks clarification on the derivative of the constant term, 258, which is crucial for correcting their calculations.
Alan I
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Homework Statement

In a certain region of space, the electric potential along the x-axis is given by:

V = 111x3 - 517x - 258 where V is in Volts and x is in meters.

Find the force F (magnitude in N and direction) felt by a -444 μC point charge at point (56.5 cm,0). (For direction, all you need is the sign.)

Homework Equations


E=dV/dx
F=qE

The Attempt at a Solution


[/B]
dV/dx=d/dx(111x3-517x-258=333x2-517-258=E

⇒ E(0.565m)=-668.7 N/C

⇒F=qE=(-444*10-6)*(-668.7)≅0.297

The answer turned out to be wrong so if someone can give me a hint towards where my mistakes are I would greatly appreciate it!
 
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What is the derivative of 258 with respect to x?
 
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Likes Alan I
Orodruin said:
What is the derivative of 258 with respect to x?

Thanks!
 
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