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 1 st and 2 nd 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 object  Forces 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 1 st and 2 nd 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 1 st Law – Law of Inertia2 nd Law a=acceleration (m/s 2 ) F=Force (N) M=mass (kg) newtons kilograms This means sum

Newton’s 1 st 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/s 2 What does 0 acceleration mean about velocity?  Velocity is constant How does this relate to Newton’s 1 st 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/s 2, 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 book  Pages  Discuss the steps for drawing a free-body diagram with person next to you.

Car towing Example Page

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