1. Review- What is happening in this video? How? Review- What is happening in this video? How? http://player.discoveryeducation.com/index.cfm?guidAssetId=69D515CC-CFDF-4DB2-9F6D- 386F68CD4E02&blnFromSearch=1&productcode=US#

2. Objectives Review- Entrance Ticket. Weight Vs. Mass Distinguish between force and net force. Equilibrium rule.

3. Weight VS. MASS  Force of gravity acting on an object  http://www.explorat orium.edu/ronh/weight/ index.html  Amount of Matter an object contains

4. What is Force?  Force is a Push or a Pull  Forces are vector quantities - they have a magnitude (How Much) and a direction Ex.: 10 N to the right  Forces are shown with arrows Point in the direction which it is being applied. The length of the arrow shows the magnitude (how much) of the force.

5. Net Force (Unbalanced Force)  Total force being exerted on an object.  Ex. Pull a box w/ net force of 5 N,  A Friend pulls a box w/ net force of 5 N  How much total force is being pulled?

6. Net Force  If no forces act on an object, the net force on the object is zero.  Additional Examples-  http://www.batesville.k12.in.us/physics/phynet/mechanics/newton1/the_net_force.html

7. Net Force Activity

8. Normal Force  The force on an object that is in contact with a surface –It is perpendicular to the surface –It usually is the force opposite of the weight of the object.

9. Equilibrium When the net force on something is zero: That something is in mechanical equilibrium. What is equilibrium? Equilibrium means a state of physical balance.

10. Equilibrium Equilibrium Equilibrium Rule: ∑ F = 0 ∑ stands for the “vector sum of” F stands for “forces”

11. Equilibrium Equilibrium Rule Continued: The rule says that the forces acting in one direction on an object must be balanced by forces acting in the opposite direction. Example: Forces acting upward must be balanced by forces acting downward. In essence, they must cancel each other out.

12. Static Equilibrium  Static means “not moving.”  If an object is not moving, it is in static equilibrium –This means that the weight of the object is canceled out by the normal force.

13. Dynamic Equilibrium  Dynamic means “moving.”  An object is in dynamic equilibrium when it is moving with a constant velocity. –Example – The force applied to the car is equal to the friction acting against it.