Catalyst – October (Prime # between 11 and 17), 2009

Objectives SWBAT Review for Unit 3 Test!!!!

Catalyst Explain how the following rules dictate how we write an orbital

diagram: Pauli exclusion principle Aufbau Principle Hund’s Rule

Take out your review sheets and begin working. Write answers on a separate sheet of paper. (you have 45min to complete it)

October (40+16)/2

Objectives SWBAT differentiate between contact and field forces SWBAT Demonstrate the use of Newton’s 1st and 2nd Laws

Catalyst #34 (Ch. 4)– In a friendly game of handball you hit the ball

essentially at ground level and send it toward the wall with a speed of 14 m/s at an angle of 34° above the horizontal. How long does it take for the ball to reach the wall if it 3.8 m away? How high is the ball when it hits the wall?

Force and Mass

A force is a push or pull on an objectForces will cause a change in velocity.Forces are vectors

They have magnitude and direction

Mass is a measure of the amount of matter in an object

2 Kinds of Forces Contact Force – forces that arise from the

physical contace of two objects

Field Forces – forces that exist between objects even in the absence of physical contact between the objects

Drop the ball…

Newton’s 1st and 2nd Law

An object at rest remains at rest as long as no net force acts on it

An object moving with constant velocity continues to move with the same velocity as long as no net force acts on it

1st Law – Law of Inertia 2nd Law

aFm

a=acceleration (m/s2)F=Force (N)M=mass (kg)

newtonskilograms

This means sum

Newton’s 1st Law Demonstration

Which way will the water fall if the cup starts at rest and is pushed forward?

Which way will the water fall if the cup is in motion and is stopped?

Physics Book and pen example

Let’s think about it - T/W/P/S

What does acceleration equal if ΣF is 0?Acceleration is 0m/s2

What does 0 acceleration mean about velocity?Velocity is constant

How does this relate to Newton’s 1st Law?

Using Newton’s Laws

The net force acting on a Jaguar XK8 has a magnitude of 6800 N. If the acceleration is 3.8 m/s2, what is its mass?

Free-Body Diagrams

A Free-Body Diagram is a picture of all the forces acting on an object.

Read the free-body diagram section of the bookPages 127-128Discuss the steps for drawing a free-body diagram with

person next to you.

Car towing Example

Page 127-128

Group Practice

On whiteboards in your groups answer numbers 3 and 4 in your books