1. Newton’s First Law
Objects at rest stay at rest, objects in motion stay in motion, unless acted on by an outside force.

2. Outside Forces: Push Pull Gravity Electric field Magnetic field
Friction

3. Force Diagram Introduction

4. 1. Two children fight over a toy
1. Two children fight over a toy. Child A pulls to the left with 25N of force while child B pulls to the right with 20N of force. Draw a force diagram AND a net force diagram for this situation.

5. 2. A man walking his dog. If the dog pulls down on the leash with a 75N force 35degreed to the horizontal, what at the x and y components of the dogs pull?
Include a force diagram!

6. 3. At the pep-rally, the freshman pulled on the tug-rope with 250N to the east, the sophomores pulled to the west with 365N, the juniors pulled north 565N and the seniors pulled south with 575N. What is the net force on the tug rope?
Include a force diagram.

7. Draw a free body diagram Calculate the net force.
Three muscles connect the femur to the hip bone. Find the x and y components of each muscle and calculate the net force and direction between to two bones. Muscle 1 pulls 48 degrees from the horizontal with 8 N of force. Muscle 2 pulls 78 degrees from the horizontal with 16 N of force. Muscle 3 pulls 104degrees from the horizontal with 4N of force.
Draw a free body diagram
Calculate the net force.