Question

DUUUUUU
TC) May increase or decrease.
(D) Remains constant
A particle of mass 2 g and charge 1uC is held at rest on a frictionless horizontal
at rest on a frictionless horizontal surface at a distance of
1 m from a fixed charge of 1 mC. If the particle is released it will be repelled. The speed of the particle
when it is at distance of 10 m from the fixed charge is:
(A) 100 m/s
(B) 90 m/s
(C) 60 m/s
(D) 45 m/s
On (E) : Potential Energy of a system of Point Charges
Six charges of magnitude + q and -9 are fixed at the corners of a regular hexagon of edge length a as
shown in the figure. The electrostatic potential energy of the system of charged particles is:
+
9​

Answer 1

Answer:

Potential at 1 m from the charge 

VA=1K×10−3

Potential at 10 m from the charge

VB=10K×10−3=K×10−4

potential diff =VA−VB=K(10−3−10−4)

Its velocity at 10 m is V, then

21×mv2=(VA−VB)q

21×2×10−3v2=K×10−6(1−101)×10−3

v2=K×109×10−6

9×109×109×10−6=81×100

v=90m/sec