When a ball is rolled across a flat floor with a force of 40 N, friction acts against it with a force of 10 N. What is the total force acting on the ball?

Question

Quizplus · Accepted Answer

The net force acting on an object is the sum of all the forces acting on that object. In this question, the ball only has two forces acting on it: the applied force (40 N) and friction (10 N). They act in opposition to one another, so they have opposite signs in the following equation:
Net force = Applied force + Friction force
Net force = 40 N + (-10 N)
Net force = 30 N
Remember that friction is working against the applied force (in the opposite direction), so it is a negative value.

When a Ball Is Rolled Across a Flat Floor with a Force