A charge of 1 C is at (3,-2) and a charge of -3 C is at ( -4,-1) . If both coordinates are in meters, what is the force between the charges?

1 Answer
Mar 5, 2017

5.4xx10^8N attractive force.

Explanation:

The distance between them can be found by subtracting x's and y's and doing Pythagoras':

r = sqrt((3--4)^2+(-2--1)^2) = sqrt50 = 5sqrt2

The electrical force is given by

F = k(Q_1Q_2)/r^2

where k~~9xx10^9 is Coulomb's constant, Q is the charges, and r is the distance which we just worked out.

Using the values we know,

F = 9xx10^9 xx (1 xx -3)/(5sqrt2)^2 = (-2.7xx10^10)/50

=-5.4xx10^8N

Since the charges are opposite, they are attractive, so even though the force has a negative symbol, that means they are pulling together, not pushing apart.