Two charges of # -1 C # and # -3 C# are positioned on a line at points # -5 # and # 2 #, respectively. What is the net force on a charge of # 4 C# at # 1 #?
The net force is
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 unlike charges, they attract. So,
This force acts toward the
Since the two forces act in opposite directions, we subtract the two values to get the net force