Answer to Question #264972 in Physics for MCC

Question

Eight boys are equally spaced about a pushball and each exerts a force upon it toward the center, as shown. Each boy in positions 1, 3, and 7 exerts a force of 70 N, and the rest of the boys exert 50 N each. What force is needed to keep the ball at rest?

Answer 1

Each pair of forces of equal magnitude cancels out, they are balanced. Forces 1 and 5 are unbalanced. So, we need to add 20 N more in the direction of force 5 for the ball to be in equilibrium.