On a chessboard, a king sits at a position +12cm from the lower left corner. A knight is +5cm from the same corner along the same straight line. What is the displacement from the king to the knight?

The protons in a nucleus are approximately 2 ✕ 10^−15 m apart. consider the case where the protons are a distance d = 1.93 ✕ 10^−15 m apart. calculate the magnitude of the electric force (in n) between two protons at this distance.