Question

Four people are pulling on ropes attached to the cart to the left and three are pulling right. Each person is pulling the cart with a magnitude of 20 N. What is the magnitude of the net force and in which direction will the cart move?

• A. 20 N, right
• B. 40 N, left
• C. 20 N, left
• D. 80 N, right

Answer 1

The correct option is C 20 N, left

When two forces are applied at the same point but in opposite directions, then the resultant force is equal to the difference of the forces acting separately. Each person is applying a force of 20 N to pull the cart. The total force applied to the left side by 4 people will be 4 $\times$ 20 N = 80 N. The total force applied to the right side by 3 people will be 3 $\times$20 N = 60 N. The net force will be the difference of both the forces, i.e. 80 N - 60 N = 20 N. The direction of resultant force will be the direction in which the larger force acts, i.e. to the left side.