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Tuesday, November 15, 2011Bellringer
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!
CHAMPsC: 0 (when the bell rings)H: quietly ask a
neighbor; after bell, raise hand
A: independent workM: 0 (after bell rings)P: silently completing
bellringer
Balanced and Unbalanced Forces
Introduction to Unit 3 – Forces and Motion
Forces and Motion NotesPassing Lane Notes
1. Key Idea Detail Detail
2. Key Idea Detail 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?
1 2 3 4
0% 0%0%0%
A. A pushB. A pullC. Anything that causes a change in
motionD. All of the above
Units are Newtons (N) 1N=1kg m/s2 (mass x acceleration)
Force
Forces come in pairs Forces have a magnitude and a
direction
5N, north (up) Magnitude: 5NDirection: 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 2
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1. True2. False
What units are used to measure forces?
1 2 3 4
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1. A. Grams2. B. Meters per second3. C. Newtons4. D. Arrows
What symbol is used in diagrams to indicate a force?
1 2 3 4
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1. A star2. An arrow3. A dotted line4. 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!
CHAMPsC: 0 (when the bell rings)H: quietly ask a
neighbor; after bell, raise hand
A: independent workM: 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. 2000 NewtonsB. 5000 NewtonsC. 3000 NewtonsD. 8000 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. 2000 NewtonsB. 4000 NewtonsC. 6000 NewtonsD. 8000 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. YesB. 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 NotesPassing LaneWrite 3 questions that can be answered using today’s notes. (*Place the questions next to the key ideas.)
Notes1. Key Idea
Detail Detail
2. Key Idea Detail 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.)