Question

A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move. Which statement best describes the motion of q after it is released?
(A) As it moves farther and farther from Q, its speed will keep increasing.
(B) As it moves farther and farther from Q, its speed will decrease.
(C) As it moves farther and farther from Q, its acceleration will keep increasing.
(D) Its speed will be greatest just after it is released. Its acceleration is zero just after it is released.

Answer 1

Answer:

(A) As it moves farther and farther from Q, its speed will keep increasing.

Explanation:

When a positive charge Q is fixed on a horizontal frictionless tabletop and a second charge q is released near to it then according to the Coulombs law the force acting on it decreases with the square of the distance between them.

Mathematically:

$F=\frac{1}{4\pi.\epsilon_0} \times \frac{Q.q}{r^2}$

where:

r = distance between the charges

$\epsilon_0=$ permittivity of free space

By the Newtons' second law of motion if the we know that the acceleration is directly proportional to the force applied. So as  the distance between the charges increases the its acceleration also decreases therefore now the charge feels less acceleration but still continues to accelerate with a fading magnitude.