5.3 Net Force and Equilibrium What is a Force? Part 1

Net Force Net Force: The sum of all forces acting on an object - remember direction!!!

Net Force If the net force is NOT ZERO, there will be a change in an object’s motion.

Equilibrium When the forces are balanced, the net force is zero and the object is in equilibrium. 4

Solving Equilibrium Problems Is this object in equilibrium?

Normal Force - occurs when an object is in contact with a surface - equal to the force pressing the object into the surface

The Free Body Diagram How do you keep track of many forces with different directions? Draw a free-body diagram that contains the objects, like a book on a table. 7

Net Force What forces are acting on you right now? Video Clip Part 2

The Free Body Diagram Draw free body diagrams that illustrate the following forces: You sit in your desk. Your desk weighs 50 N and you weigh 80 N. Don’t forget to draw the normal force! A 150 N child rides a 25 N skateboard and moves to the right with a force of 10 N. Rolling friction between the wheels and ground is 5 N. Don’t forget to draw the normal force! 9