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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)

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Tuesday, November 15, 2011

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### 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

Passing Lane

Notes

• Key Idea

• Detail

• Detail

• 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?

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/s2 (mass x acceleration)

### Force

• Forces come in pairs

• Forces have a magnitude and a direction

Magnitude: 5N

Direction: north (up)

5N, north (up)

• Forces can be represented by arrows.

• The size of the arrow represents the magnitude and the point shows its direction.

• True

• False

### What units are used to measure forces?

• A. Grams

• B. Meters per second

• C. Newtons

• D. Arrows

### What symbol is used in diagrams to indicate a force?

• A star

• An arrow

• A dotted line

• 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. 2000 Newtons

B. 5000 Newtons

C. 3000 Newtons

D. 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 Newtons

B. 4000 Newtons

C. 6000 Newtons

D. 8000 Newtons

### Group Question 4

• Draw arrows showing the individual and combined forces of the tugboats

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’snotes.

(*Place the questions next to the key ideas.)

Notes

• Key Idea

• Detail

• Detail

• 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.)