Introduction to Mechanics 2.1 notes LEAP DAY!!! February 29, 2016 Introduction to Mechanics 2.1 notes

Warm up As a table, discuss and come up with a definition for MOTION

Aristotle 384-322 BC Old Greek Philosopher He lived from 384-322 BC He studied from Plato in his academy for 20 years He became the tutor of young Alexander the Great

Aristotle on Force A force is required to keep an object moving 2000 years pass….

Alexandrian Conquest

Roman Conquest

Crusades

Dark Ages

Galileo 1564-1642 Lived from 1564-1642 AD He made a big discovery that proved Aristotle was wrong Dropped two weight objects and they both landed at the same time So Aristotle must have been wrong about forces being necessary to keep objects moving. Galileo said that force is required to START an object moving, but none is required to keep it moving (when there isn’t friction)

Inertia Objects in motion want to stay in motion Objects at rest want to stay at rest Unless acted on by another force.

Mass and Inertia Mass is actually a measurement of inertia. More mass = more inertia Less mass = less inertia

Check it out… https://www.youtube.com/watch?v=vfnt8Sdj7cs Inertia Demos: Redo inertia “magic trick” with hoop and pennies/dice Paint stick and newspaper karate chop Hammer and bowling ball Card and poker chips Magic Broom Meter vs Newton-Meter drop

Lesson Recap A ball rolling on a pool table slowly comes to a stop. How would Aristotle explain this behavior? How would Galileo explain it? How would you explain it?

Reaction Time Activity Work with partner at table group Record distance in METERS please In your analysis---EVERY number needs a unit! Discuss the discussion questions (you don’t need to write anything down) Done early? Do the extra challenge!

Speed vs. Velocity Distance vs. Displacement Definitions of Δ and (-) March 3, 2016 Speed vs. Velocity Distance vs. Displacement Definitions of Δ and (-)

Speed Speed is a scalar quantity Formula: 𝑆𝑝𝑒𝑒𝑑= 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑖𝑚𝑒 Scalar means it is just a number without direction Formula: 𝑆𝑝𝑒𝑒𝑑= 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑖𝑚𝑒

Velocity Velocity is a vector quantity Formula: Vector means it has both a number AND direction Formula: 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦= ∆ 𝑑𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡 ∆ 𝑡𝑖𝑚𝑒 Δ means “change in” which is calculated = (final – initial) ( - ) in physics just indicates direction

Distance vs. Displacement Distance (scalar) Is how much ground an object has covered Displacement (vector) Is the overall change in position Watch this! https://www.youtube.com/watch?v=V8hJhTE3bUk Now let’s try it! Practice Questions—write on white boards http://www.physicsclassroom.com/class/1DKin/Lesson-1/Distance-and-Displacement

Maps Graphs Instantaneous vs. Average March 7, 2016 Maps Graphs Instantaneous vs. Average

Motion Maps Each dot represents the position at an equal time interval Use the space below this definition in your notes to draw in a sample motion map… Bowling lab with sticky notes Jogger vs. sprinter Make up your own

Graphs Position vs. Time graphs---Slope = velocity value As demonstrated in your Dance Party Lab

Average vs. Instantaneous “Average” velocity is a measure of the total distance traveled in a certain period of time. “Instantaneous” velocity is the exact speed at a specific point in time Example: I went to see Zootopia with a gaggle of junior high girls from my church on Saturday. It took me 10 minutes to get from church to the theater 3 miles away. My average speed was:____________ My instantaneous speed was all over the place.

March 16, 2016 Acceleration

Translations Recall that on a displacement vs. time graph SLOPE = VELOCITY value But what about the slope of a velocity vs. time graph? (Think about your Tickticktick lab and yesterday’s instantaneous velocity activity) What are the units? What does the measurement mean?

Acceleration (vector) The formula for acceleration is: 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛= ∆ 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 ∆ 𝑡𝑖𝑚𝑒 In a velocity vs. time graph SLOPE = ACCELERATION value

Summary of how to represent motion in graphs

Review Day Tasks: Tom’s graph matching (create acceleration vs. time) Update Instantaneous Velocity Activity (turn in) Check answer key for Acceleration Practice at front (turn in) 4. Work on any missing work or make up labs 5. Go over missing work with Mrs. Peterson when called

Test Corrections Instructions Use a different color than your original writing Write directly on test (unless not enough room) Write the correct answer AND EXPLAIN WHY IT IS CORRECT Return directly to Mrs. Peterson Absolutely NO phones in class today at all This is your only warning…