333 PHYSICS - UNIT 2 Explanations as to why things occur versus just observation.

Copernicus & the moving Earth What idea did Copernicus propose that revolutionize science? What view was held prior to Copernicus proposal?

In the 1500’s, Galileo reasoned…

In the year 1642, Galileo died and Issac Newton was born In the year 1642, Galileo died and Issac Newton was born. He was a genius who essentially wrote the book of physics in 18months. He furthered Galileo’s idea and generated Newton’s Laws of Motion.

Law of INERTIA OR 1ST LAW: Objects tend to ______________________________ Object at rest ________________________________ Unless object is acted on by a FORCE along the path of motion ____________________________ A force is a ____________________ A Newton is the unit of force (N)

Mass Mass is measured in kilograms (kg). Mass is the measure _____________ Mass is measured in kilograms (kg). Mass is something _________________ Mass is not weight. You can change your weight without changing your mass. How?

Which path would a marble follow after exiting the circular track?

Explain the purpose of seatbelts using the concept of inertia.

An argument against a moving Earth (Copernicus) was the following: Consider a bird sitting at rest at the top of a tall tree. If the earth is really moving around the sun at 30km/s and also rotating at 1000mph, then how does a bird dive down to catch a worm? Why doesn’t classroom wall hit us if we jump up in air?

3rd LAW or Action/Reaction For every ACTION FORCE This is due to an interaction between 2 objects. Forces occur in pairs!

Scale Demo: one scale pulls on the other and vice versa

Walking or Jumping Swimming Forces occur in pairs. Action-reaction pairs do NOT cancel one another out…WHY?

Ducks fly in a V formation because air pushed downward at the tips of their wings swirls upward, creating an updraft that is strongest off to the side of the bird. A trailing bird gets added lift by positioning itself in this updraft, pushes air downward, and creates another updraft for the next bird, and so on. The result is a flock flying in a V formation.

Use 3rd law to describe the motion of: A Rocket taking off A helicopter hovering over the ground

Question: A loaded school bus hits a bug and kills it Question: A loaded school bus hits a bug and kills it. Which body receives the greater force of impact, bug or bus?

Fan for boat with no wind?

Who pulls harder on the rope? Who wins the tug of war?

NET FORCE (FNET ) Net = Net Force =

Net Force causes Mass Resists

TYPES OF FORCES Normal force = Friction force =

Tension force = Weight force =

Newton’s 2nd Law

Explain.