Free Body Diagrams and Newtons Laws Free Body

Free Body Diagrams and Newton’s Laws

Free Body Diagram A diagram of all the external forces on an object. The object is drawn as is floating in space (“free”). • Only include forces on the diagram, not other vectors such as acceleration or velocity. • Only include the actual individual forces, not components or net forces.

Example Ftable Free Body Diagram Fg

Object or System of Objects System

Problem #1 A 55 N box is at rest on a table. What is the force of the table on the box?

Ftable Fg

Problem #2 A 20 kg box is at rest on a table. What is the force of the table on the box?

Ftable Fg

Problem #3 Two 20 kg boxes are tied together with a rope. A force of 40 N is applied to the block on the right. What is the acceleration of the blocks?

Treating the boxes as one system

Problem #4 Two 20 kg boxes are tied together with a rope. A force of 40 N is applied to the block on the right. What is the tension in the rope?

Examine the forces on one box

Problem #5 Two 20 kg boxes are tied together with a rope. A force of 60 N is applied to the block on the right at an angle of 30 degrees to the horizontal. What is the acceleration of the blocks?

Treating the boxes as one system

Problem #6 The length of the chain between the car and the tree is 15. 0 m and the perpendicular force causes the chain to deflect 0. 5 m from the dotted line in the diagram. If the perpendicular force is 100 N what is the force T on the car if the car doesn’t move?

Examine the point in the chain where the perpendicular force is applied T T F┴