Example: a positive charge Q1 = +Q is located a distance d along the y-axis from the origin. A second positive charge Q2 = +Q is located at the origin and a negative charge Q3 = -2Q is located on the x-axis a distance 2d away from Q1. Calculate the net electrostatic force on Q1 due to the other two charges. y Q1=+Q d 2d Q2=+Q x Q3=-2Q

Calculate the net electrostatic force on Q1 due to the other two charges. y F2 Q1=+Q  F3 d 2d  Q2=+Q x Q3=-2Q Note: F2 and F3 are not drawn to scale (F3 is “too long”).

Calculate the net electrostatic force on Q1 due to the other two charges. y F2 Q1=+Q  F3 d 2d  Q2=+Q x Q3=-2Q Note: F2 and F3 are not drawn to scale (F3 is “too long”).

Comments: Once you have become an expert at problems like this, you can combine and perhaps even skip some steps. Skipping steps on work to be graded is not recommended! You may express your answer in unit vector notation, as on the previous slide. Or you may write You may also express your answer as a magnitude and direction. All three of the above ways of writing F completely specify the vector.

y F2 F Q1=+Q  F3 d 2d  Q2=+Q x Q3=-2Q If Q1 were free to move, what direction would its initial acceleration be? How would I calculate the acceleration? Would the acceleration remain constant as Q1 moved? Could I use the equations of kinematics (remember them from Physics 1135?) to describe the motion of Q1?