assignment #2 car crashes lo: i can model the sum of ... · 2/8/2019  · assignment #2 car crashes...

LEVEL ZERO VOICECATALYST (10 minutes, individual work):

1. What is the total force on the object in the vertical plane? Horizontal?

What is the direction of movement?

2. Compare and contrast oceanic/oceanic subduction and oceanic/continental subduction.

3. Draw a picture of sea floor spreading, what does it create?

AGENDA

1. Notes

2. Investigation

3. Class discussion

HOMEWORK

1. Complete assignments

Assignment #2 Car CrashesLO: I can model the sum of forces acting on an object using observational descriptions (down, up) and symbols (arrows). EQ: How do you describe speed? Why do things bounce back when they collide?

• Force of gravity is pushing down on cup

• Friction of the cup on the table cloth is pulling the cup in direction of the tablecloth pull

•Normal force: the support force exerted upon an object in contact with another stable surface

• Friction keeps the cup on the table cloth and will go in the direction of the tablecloth pull

• The tablecloth must be pulled fast enough to overcome friction

• The cup must be heavy enough to stay in the same place

Car Crash: (0-3:00) https://www.youtube.com/watch?v=r8E5dUnLmh4

•Notes side

•Car Quickwrite: Write a claim about what you think will happen to the cars.

•Task Description: To investigate laws of motion by observing 3 car scenarios and to model forces acting on an object. To calculate speed.

•How to use the speed formula

•Task Card: Exploring Motion and Forces

•You will be filling out the data handout

•Discuss Class Data:

•What did you notice?

•What are you unclear about still?

•What information could be gathered at each set-up?

•Discuss Class Data:

•What did you notice?

•What are you unclear about still?

•What information could be gathered at each set-up?

•What caused the cars to slow down?

Car Crash: (0-3:00) https://www.youtube.com/watch?v=r8E5dUnLmh4

Notes on Forces

• Force – a push or pull exerted by an object on another object

• EX: hand exerts force on bow

• Contact force: force that is exerted when two objects are touching

Force- a push or pull

• Noncontact force: force that one object exerts on another when they are not touching

• Examples: • Jump in the air, pulled down

• Gravitational force exerted by Earth

• Magnetic force

• Electric force

Force is a vector• Force has a magnitude (size) and

direction

• Unit for force is the newton

• Newton = N

• Represented by an arrow in the direction of motion

• Length represents size (speed)

• You use 20 N of force to lift a 2 L bottle of water

Combining Forces – same direction

• When forces are acting on an object in the same direction, ADD them to get the net force

• Force 1 + Force 2 = NET FORCE

**forces are vectors so you must specify the direction

Combining Forces – opposite directions

• When two forces are in opposite direction acting on the same object:

• Choose a positive and negative direction, then add the forces

1. Choose a positive direction (ex: right, +150 N)

2. The other direction is a negative number (Ex: left, -100 N)

3. Add them together (Ex: 150 N + (-100 N) = 50 N )

Unbalanced and balanced forces

• Unbalanced forces: an object moves when the net forces on an object is not zero

• Balanced forces: when the net forces on an object is zero, it doesn’t move

Unbalanced forces and Motion

• Kick a ball the net force moves the ball

• Unbalanced forces on objects cause them to move

• Unbalanced forces on an object cause them to accelerate

Balanced Forces and Motion

• When the forces on an object are balanced, the object does not move

Types of Forces

1. Gravity - Attractive force that exists between all objects that have mass• The attractive force depends on mass of the objects and distance between

them

2. Friction – force that opposes movement between two surfaces in contact

3. Elastic Forces – force exerted by a material when it is stretched or compressed• Normal force (compression) – force exerted by an object that is perpendicular

to the surface of the object

Normal force

• Normal force- force exerted by an object that is perpendicular to the surface

• Normal Force: the force that the ground pushes back up with, if there is no normal force, a person would sink into the ground

• A type of elastic force because the two objects push against each other

Process your notes

Highlight/box/circle key words

LEVEL ZERO VOICEPROCESSING TASK (10 minutes, individual work):

Draw a model of each of the three scenarios. • Describe what happened in each scenario including force arrows

(showing magnitude, or size, differences)• Include force of friction, normal force, and gravity

AGENDA

1. Discussion

2. Investigation

3. Class discussion

HOMEWORK

1. Complete assignments

Assignment #2 Car CrashesLO: I can model the sum of forces acting on an object using observational descriptions (down, up) and symbols (arrows). EQ: How do you describe speed? Why do things bounce back when they collide?