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

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

Is the force Balanced orunbalanced?

Unbalanced-

What is the net force and in which direction is it going in?