NET FORCE Definitions of Force is a push

NET FORCE

Definitions of Force is a push or a pull acting on an object. Force is a vector. (magnitude & direction)

More on Force… Forces can change the motion of an object SI unit = newton (N) Net force is the vector sum of all forces acting on an object. Since force is a vector, the net force will have magnitude and direction.

FREE BODY DIAGRAM We will draw what is called a free body diagram to show forces acting on the object Draw the object as a box Draw all forces acting on it with arrows coming out of the box in the direction they act

More on Net Forces in same direction: add Net force in same direction as forces. See picture 2 Forces in opposite directions: subtract. Net force in direction of larger force. See picture 3 Equal forces in opposite directions : subtract. Net force is zero See picture 1

What is the net force acting on each object below? http: //www. slideshare. net/meenng/forces

Balanced forces Net force = 0 Balanced forces do NOT cause any change in an object’s motion.

Balanced forces

Unbalanced force Net force ≠ zero Causes an object to change its motion Many unbalanced forces causing motion: video

Example Two tugboats are moving a barge. Tugboat A exerts a force of 3000 Newtons on the barge. Tugboat B exerts a force of 5000 Newtons in the same direction. What is the combined force on the barge? Draw arrows showing the individual and combined forces of the tugboats.

Example Now suppose that Tugboat A exerts a force of 2000 Newtons on the barge and Tugboat B exerts a force of 4000 Newtons in the opposite direction. What is the combined force on the barge? Draw arrows showing the individual and combined forces of the tugboats.

Example Could there ever be a case when Tugboat A and Tugboat B are both exerting a force on the barge but the barge doesn't move? Draw arrows showing the individual and combined forces in such a situation.