1. Newton’s Second Law http://www.youtube.com/watch?v=UyI3IL 46yq4

2. Do-Now O Write down what you remember from the lab on Friday. O What is the relationship between force and acceleration? What is the relationship between mass and acceleration?

3. Force and Newton’s Second Law O What is force? O Any push or pull O When the force increases and the mass stays constant, the acceleration increases O When the mass increases and the force stays constant, the acceleration decreases

4. Newton’s Second Law O F net = ma O F net = force (in Newtons) O m = mass (in kg) O a = acceleration (in m/s 2 )

5. Weight O the effect of the acceleration due to gravity O Always directed downward O Dependent on location O Weigh more or less on the moon? Why?

6. Mass O Amount of matter in an object O Constant for a particular object O Independent of location O Do you have a different mass on the moon?

7. Weight Equation O F g = mg O F g = force due to gravity (in Newtons) O m = mass (in kg) O g = acceleration due to gravity (10 m/s 2 )

8. Weight in an Elevator O http://www.youtube.com/watch?v=2k-2IlJcaHg http://www.youtube.com/watch?v=2k-2IlJcaHg

9. Net Force and Acceleration O Net force: the result of all forces exerted on an object O If forces are exerted in the same direction, they are added O If forces are exerted in opposite directions, they are subtracted O Acceleration is always in the direction of the net force (largest force) O If the Net force is zero, the object is not accelerating O Can it be moving though?

10. Free Body Diagrams O Drawing to help understand forces O Draw arrows away from the object to represent forces

11. Equilibrium O When the acceleration of the object is zero O Net force is also zero O Two types O Static: Object is not moving O Dynamic: Object is moving at constant velocity

12. Static Objects O If the net force is zero AND the object is not moving, it is said to be static O Weight pulls objects down O Normal force O Supports them from falling O Acts perpendicular to a surface

13. And now your favorite professor… O http://www.youtube.com/watch?v=_XJrY2s KfFQ http://www.youtube.com/watch?v=_XJrY2s KfFQ