Tuesday, November 15, 2011 Bellringer If you have paperwork to turn in, please leave it on your desk. I will get it. Copy the “I can” statement from the board. Fill out your agenda. Remember CHAMPs expectations! CHAMPs C: 0 (when the bell rings) H: quietly ask a neighbor; after bell, raise hand A: independent work M: 0 (after bell rings) P: silently completing bellringer

Balanced and Unbalanced Forces Introduction to Unit 3 – Forces and Motion

Forces and Motion Notes Passing Lane Notes 1. Key Idea  Detail 2. Key Idea  Detail

What is a force? A force is a push or pull that causes an object to move, stop, or change direction

What is a force? A. A push B. A pull C. Anything that causes a change in motion D. All of the above

Units are Newtons (N) 1N=1kg m/s 2 (mass x acceleration)

Force Forces come in pairs Forces have a magnitude and a direction 5N, north (up) Magnitude: 5N Direction: north (up)

Forces can be represented by arrows. The size of the arrow represents the magnitude and the point shows its direction.

Forces always exist in pairs. 1. True 2. False

What units are used to measure forces? 1. A. Grams 2. B. Meters per second 3. C. Newtons 4. D. Arrows

What symbol is used in diagrams to indicate a force? 1. A star 2. An arrow 3. A dotted line 4. The letter “F”

NET FORCE When all forces are combined together it is called the net force. Forces in the same direction combine by addition. Forces in opposite directions combine by subtraction.

Addition of Forces

Wednesday, November 16, 2011 Bellringer If you have paperwork to turn in, please leave it on your desk. I will get it. Copy the “I can” statement from the board. Fill out your agenda. Remember CHAMPs expectations! CHAMPs C: 0 (when the bell rings) H: quietly ask a neighbor; after bell, raise hand A: independent work M: 0 (after bell rings) P: silently completing bellringer

Balanced and Unbalanced Forces Forces occur in pairs and they can be either balanced or unbalanced

Balanced Forces Balanced forces do not cause change in motion Net Forces=0 They are equal in size and opposite in direction

Group Question Draw a Balanced Seesaw Showing Forces

Unbalanced Forces An unbalanced force always causes a change in motion. When unbalanced forces act in opposite directions you can find the net force  Net force Magnitude  The difference between the two forces Direction  Direction of the largest force

Unbalanced Forces 3 N, right 6 N, left = 3N, left

Unbalanced Forces 4 N, left 10 N, right = 6N, right

Unbalanced Forces 5 N, right + 10 N, right =15N, right

Group Question 2 Draw An Unbalanced Seesaw Showing Forces

Two tugboats are moving a barge. Tugboat A exerts a force of 3000 newtons on the barge. Tugboat B exerts a force of 5000 newtons in the same direction. What is the combined force on the barge? A Newtons B Newtons C Newtons D Newtons

Group Question 3 Draw arrows showing the individual and combined forces of the tugboats.

Suppose that Tugboat A exerts a force of 2000 newtons on the barge and Tugboat B exerts a force of 4000 newtons in the opposite direction. What is the combined force on the barge? A Newtons B Newtons C Newtons D Newtons

Group Question 4 Draw arrows showing the individual and combined forces of the tugboats

Could there ever be a case when Tugboat A and Tugboat B are both exerting a force on the barge but the barge doesn’t move? A. Yes B. No

A Quick Recap Forces are a PUSH or PULL Unbalanced Forces cause a change in motion. No motion occurs when forces are balanced. Forces are measure in NEWTONS. Forces are represented by arrows. The overall force is called the NET FORCE

Forces and Motion Notes Passing Lane Write 3 questions that can be answered using today’s notes. (*Place the questions next to the key ideas.) Notes 1. Key Idea  Detail 2. Key Idea  Detail

Ender Gauge your understanding of today’s “I can” statement. (Check the line.) On the lines underneath, prove the “I can” statement. (In other words, explain the difference between balanced and unbalanced forces.)