Catalyst

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# Catalyst - PowerPoint PPT Presentation

Catalyst. 1. Sketch the picture below 2. Draw force arrows for all forces acting on the block Label all forces A block is held motionless by a rope on an incline . 4. How much will a 90 kg table weigh on Earth?

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## PowerPoint Slideshow about ' Catalyst' - cody

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Presentation Transcript
Catalyst

1. Sketch the picture below

2. Draw force arrows for all forces acting on the block

• Label all forces

A block is held motionless by

a rope on an incline

• 4. How much will a 90 kg table weigh on Earth?
• 5. If this table is taken to Mars, and it has a weight of 720 Newtons, what is the gravity of Mars?
Free Body Diagrams
• A diagram that shows the magnitude and direction of all forces acting on an object
Free Body Diagrams
• These are vector diagrams
• Size of arrow is the size of the force
• Direction of arrow is the direction of force
• Each force is labeled to tell us the type of force and sometimes the magnitude.
• No rule about the number of forces that must be drawn
• There is usually at least one force present but there is no limiton how many past that
Steps for Drawing Free Body Diagrams

1. Identify what object you are going to draw (usually a box) and what is happening to that object

2. Identify all forces acting on the object and the direction in which they act

3. Draw the object/box

4. Draw each force as an arrow from the box and going in the right direction

5. Label each arrow with force name & magnitude

velocity

book

Example: Free Body Diagram

Force of friction:

Ff

Normal force N

concrete

Weight

Free Body Diagrams: Common Situations
• An object sitting on a surface
Free Body Diagrams: Common Situations
• An object sliding down an incline
Free Body Diagrams: Common Situations
• An object motionless on an incline
Free Body Diagrams: Common Situations
• An object being pulled/pushed
Free Body Diagrams: Common Situations
• An object held motionless by a rope on an incline (our Catalyst)
With Numbers…
• A 500 N table sitting on the ground is pushed to the right with force 200 N.
Steps for Drawing Free Body Diagrams

1. Identify what object you are going to draw (usually a box) and what is happening to that object

2. Identify all forces acting on the object and the direction in which they act

3. Draw the object/box

4. Draw each force as an arrow from the box and going in the right direction

5. Label each arrow with force name & magnitude

Group Work
• (7 min) On a sheet of paper (each person), draw free body diagrams for the following 5 situations.
• A 0.5 N ball sits on a desk.
• A 700 N person standing on the ground is pushed to the right with force 300 N.
• A 5 N ball is thrown upward with force 100 N.
• A 600 N ice skater glides along the ice at constant speed.
• A 3 N apple falls from a tree (draw when it’s in the air)
• (15 min) In partners, go through the Science World magazines and cut out one example of each of the 8 forces from yesterday’s notes. Then tape/glue them to the boards at the front of the room.
Exit Slip

Do a quick sketch of the object to the right.

1. Draw the normal force vector

2. Draw the force due to gravity

3. Draw the force due to friction

Exit Slip

4. How many forces are acting on an object sliding across a table with friction?

a. 1

b. 2

c. 3

5. How many forces are acting on an object that is in free fall?

a. 1

b. 2

c. 3