1. Mr. Finau Applied Science III

2. What does the phrase “Everything’s relative” mean?  Observations come from a perspective  Every perspective can reveal a different conclusion

3. What does the phrase “Motion is relative” mean?  Motion depends on your perspective  An object can appear to be moving from one perspective, but not from another

4. Distance & Displacement

5. What is Speed? What is Velocity? What’s the difference?  Speed is the rate at which an object moves  “How fast an object moves”  Velocity is the rate at which an object changes position  “How fast an object moves & what direction”  Speed gives you an amount; Velocity gives you an amount and direction

6. What are the units for speed/velocity? Can you come up with an equation for it?  In metric, we use meters/seconds (m/s)  A rabbit runs 10 m in 2 seconds. How fast does it run?  A squirrel runs with a speed of 4 m/s. How far does it travel in 2 seconds?

7. What is the “ultimate speed limit”…the fastest speed that we know of?  Speed of Light  3 X 10 8 m/s  Over 671 million miles per hour!!!

8. What is acceleration? Where do you use acceleration in your life?  Acceleration is the rate at which velocity changes  Examples?  Start running from stopped position  Sliding into 2 nd base in baseball  Driving a car – push on accelerator, brake, or turn the wheel

9. What’s the difference between acceleration and velocity  Velocity is the change in position over a period of time  Acceleration is the change in velocity over a period of time

10. An apple falls from a tree; does it accelerate? Why?  Yes, a falling apple accelerates  Its speed changes from zero to moving…  Gravity causes acceleration vertically

11. What is free fall? How much do you feel like you weigh when you’re in free fall?  Free fall is when an object is only acted upon by gravity  You feel weightless  Is there a difference between Weight & Mass?  Yes, mass is the amount of matter, weight depends on gravity

12. A ball is thrown vertically upward. What happens to the ball’s velocity while it’s moving upward?  The ball slows down as it moves upward

13. What is its velocity when it reaches its maximum height? What’s happening to the direction the ball is moving at this point?  Velocity is zero; stops moving for a brief moment  The ball’s velocity is changing direction

14. What happens after the ball changes direction? What causes this?  Starts moving downward  Gravity pulls the ball downward

15. At what part(s) of the ball’s flight is it accelerating?  The ball accelerates during all parts of its flight

16. If an object has a positive acceleration, what is happening to the object velocity and distance traveled?  Velocity increases (at a constant rate)  Distance increases (exponentially)  Exponentially – travels farther & farther each second

17. If an object has a negative acceleration, what is happening to the object velocity and distance traveled?  2 possibilities:  Velocity is decreasing  Distance still increasing  Velocity is increasing in negative direction  Distance increases in negative direction

18. If a turtle slides across the beach with a constant speed of.25 m/s, what is its acceleration?  Acceleration = O  Key words – Constant Speed

19. If a car is traveling eastward, can its acceleration be in the westward direction? How?  If a car is slowing, it has a negative acceleration.  If eastward is in the positive direction, what’s in the negative?  Westward, so Yes!

20. Graphing Motion

21. Situation  Let’s discuss in terms of a car that is driving with a constant acceleration of 1 m/s 2

22. Keys to Graphing Motion  Identify which variable is the dependent variable  This is the variable on the y-axis  will change depending on independent variable on x- axis(usually time)

23. Keys to Graphing Motion  Determine what the dependent variable is doing  Whether it is:  Zero (no value; there is none)  Staying Constant (value doesn’t change)  Increasing/Decreasing at a constant rate (typically just a diagonal)  Increasing/Decreasing exponentially (typically a curve)

24. Keys to Graphing Motion  Understand what is happening to object  Imagine what the object is doing in relation to the dependent variable  Three Variables:  Distance  Velocity  Acceleration  For example – if velocity is constant, you know acceleration is zero, and distance will increase at constant rate

25. Keys to Graphing Motion  Describe/Graph the other variables vs time  Be able to fully describe what is happening to the other variables of the object  If you’re given velocity, be able to describe what is happening to its distance and acceleration

26. Back of Worksheet Given: _________________ Describe other variables

27. Review – Quiz tomorrow  Review your notes carefully  Any questions in particular?  Remember Speed equation – 3 math questions  Hint to remember  mph = miles/hours  Review how to graph when discussing distance & velocity – 2 graphing questions