1. READ PAGES 34-37 Physics Homework

2. Terms used to describe Physical Quantities Scalar quantities are numbers without any direction Vector quantities that have both magnitude and direction  If asked to determine the magnitude of a vector quantity, just report a numeric answer

3. Motion Definition - the change in position or location of an object  Motion is relative  must be described as it relates to a frame of referenceframe of reference  Examples: x – y plane compass points

4. How far does an object move? Distance is a scalar quantity that describes total length that an object has traveled from its origin Displacement is a change in position having both magnitude and direction  Equal to the final position minus the initial position  Displacement = d f - d i

5. Average velocity is a vector quantity describing the time rate of change of the displacement of an object Average speed is the time rate of change in distance of an object  Scalar Quantity

6. Avg velocity =displacement time Units: meters/second (m/s)

7. A car traveling at 15 m/s speeds up at a constant rate to 35 m/s over a 10 s time interval. What is the average speed of the car during this time interval? How far does this car travel during this time interval?

8. Acceleration Definition: the time rate of change of the velocity of an object  Vector quantity acceleration = change in velocity time a =  V= V final - V initialt Units: meters/ second 2

9. Can the acceleration of an object be negative? What does it mean?  Object is slowing down.

10. Do Now:Homework: A car traveling at 45 m/s east is slowed uniformly at a rate of 1.5 m/s 2 for 10.0 s. What is the final velocity of the car in m/s? Answer questions on pages: 64 #6, 7, 8, 10, 11 69 #26, 27, 29

11. How can we determine the displacement of an object as it undergoes uniform acceleration? Equations can be derived by manipulating previously learned equations.  Rearrange the average velocity equation to solve for d  When solving for the average velocity of an object when an initial and final velocity are known we used the following equation:

12. We can substitute the equation for avg v into the equation for d as follows:

13. In the do now question the equation for acceleration was rearranged to solve for V f. Substitute this in for the V f in the equation we just determined and combine like terms.

14. Practice An airplane, starting from rest, undergoes an acceleration of +3.0 m/s 2 for 30.0 s before leaving the ground. What is the airplane’s displacement during this time interval?

15. Graphic Analysis of Displacement vs Time

16. Graphic Analysis Position versus time graphs: - slope indicates the velocity (rate of change in position) of the object - Positive slope means object moves in a forward direction - Negative slope means object moves backwards - No slope means object is at rest (not moving)

17. Do Now If the slope of a displacement vs time graph represents velocity, what would a graph of displacement vs time look like for an object that undergoes uniform acceleration?

18. How can we determine the instantaneous velocity of an object from a displacement vs time graph? Instantaneous velocity – the speed and direction that an object has at a particular point in time Determining instantaneous velocity from a displacement vs time graph - identify the time in question - draw a line tangent to the point - determine the slope of the tangent line

19. Do Now Using the instantaneous velocities previously calculated, plot a graph of instantaneous velocity vs time.  What is the relationship between the velocity and time for this motion?

20. Does it look like this?

21. How can we determine the displacement of an object from a velocity vs time graph? Identify the time interval in question Calculate the area under the graph. Determine the distance traveled by the object during the first 3.0 seconds. Determine the distance traveled by the object from 2.0 to 4.0 seconds.