1. Newton’s Three Laws of Motion

2. Newton’s 2 nd Law

3. 2 nd Law “The net force acting on the object will cause it to accelerate.” In other words: ΣF = Net (sum) of forces (in Newtons) m = mass (kg) a = acceleration (m/s 2 )

4. We can rewrite as The more massive an object is, the harder it is to accelerate it! 2 nd Law What is a Newton? ~Newton: the amount of force necessary to accelerate 1 kg of mass at a rate of 1 m/s 2

5. Free Body Diagrams Used to illustrate the forces acting on a particular object ALWAYS draw a free body diagram! ALWAYS include EVERY force! ALWAYS LABEL YOUR FORCES!

6. How To Draw A Free-Body Diagram 1.Draw a box to symbolize each object in the system. Each object of interest should have its own free-body diagram. Pretend the object is by itself in empty space. (It is a "free body".)

7. 2.Include all the forces acting on the body. (Don't include the forces the body causes on other objects.) 3. Draw an arrow from the box representing each force. The direction of the arrow should indicate the direction of the force. The sizes of the arrows should be proportional to their value. Label each arrow clearly.

8. A student in an elevator accelerating upward.

11. How to Solve Force Problems Draw a FBD!! Write out givens and unknowns for each axis Write out your ∑F equations for each axis Substitute Solve!

12. The Force of friction is 10 Newtons. How big of a force do you need to pull with to accelerate this box at 2 m/s 2 ? F fr = 10 Newtons 2 nd Law F pull = ? m= 3 kg