Two charges of # -4 C # and # -3 C# are positioned on a line at points # -5 # and # 5 #, respectively. What is the net force on a charge of # -3 C# at # -1 #?
The net force will be
We solve this problem by separately calculating the force acting on the
First, the force due to the
(Notice I have deliberately left out the signs on the charges. This is because I prefer to let the formulas determine the magnitude of the force. I already know the direction. Since these are like charges, they repel. So,
This force also repels the -3C charge at -1, meaning it acts to the left.
Since the two forces act in opposite directions, we subtract the two values to get the net force. Since