March 20, 2014- Happy Spring! Homework: Complete Will, Bill, and Phil worksheet- Read over Fig. 3 on page. 39 in textbook Do Now: -Write down homework, put worksheet in notebook- glue in later Update T.O.C: pg: 1: The nature of Force, pg 2: Combining Forces: Net Force/ Unbalanced Forces Open Textbook to pg. 36- Open NB. To pg 89/1

Chapter 2- Forces The Big Idea: Motion and Forces Essential Question (EQ): What causes an objects motion to change?

Force The nature of force Where does it all begin? What causes an object to start moving, stop moving or change direction? Force -Is a push or a pull- exerted by one object onto a second object. -Force is described by its strength and direction and these are symbolized with an arrow

The strength and direction a can be represented with an arrow Points in the direction of the force The length of the arrow shows its strength. **The longer the arrow the greater the force**

The Newton (N) The strength of a force is measured in the SI unit called a newton (N) One newton of force = lifting up a small lemon

Net Force/ (un)Balanced Forces Net Force – the combination of all the forces acting on an object-Determines if the object moves and which direction it moves in- It always acts in the direction of the greatest force. Unbalanced force:-} Can cause an object to start moving, stop moving or change direction- results in a net force and causes a change in motion Balanced Forces:-} Equal forces acting on one object in opposite directions- there is no change in motion and no net force

Tug-of-war? If the net force is anything other than zero (0)- forces are unbalanced and there is a change in motion

Combining forces( pg. 2 in Notebook) Look at Fig. 2 on pg. 37: When the two arrows are going in the same direction they are added together to find the net force Two forces act in opposite directions- they are subtracted (or like adding a positive # to a Negative #) *The net force ALWAYS acts in the direction of the greatest force.* A net force of zero (0) --the forces are balanced- no change in motion Strength and direction of individual forces determines the net force:

Is the force Balanced or unbalanced? What is the net force and in which direction is it going in?