Question

Eight boys are equally spaced about a pushball and each exerts a force upon it toward the center, as shown. Each boy in position 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

Solution;

Visualize the problem in a diagram;

Clearly;

7 balanced with 3

6 balances with 2

4 balances with 8

An imbalance occurs between 1 and 5;

70N-50N=20N

An additional force of 20N is needed at position 5.