1. BELLWORK 9/11/17 HOW MANY SIG FIGS ARE IN THE FOLLOWING MEASUREMENTS?
A) m
B) 5.00g
C)1250m
D) 105g
E) 3500m

2. Chapter 2-1 Displacement and Velocity

3. Motion in One Dimension
In this chapter, we will only be dealing with motion in one dimension.
Ex: A train moving either forward or backwards along the tracks. It cannot move left and right and up and down.
In further chapters, we will discuss motion in two dimensions.

4. Point A --------> Point B
Frame of Reference
Motion takes place over time and depends on the frame of reference.
In order to measure the distance of an object we must use a frame of reference.
Point A > Point B
- Your frame of reference is a point which remains fixed for the problem in question and has an origin,(starting point) from which the motion is measured.

5. Displacement is the shortest distance between the starting point and the ending point.
A change in position
Δ x = xf - xi

6. Turn to Page 41 in your books
What will you select as the frame of reference to measure the gecko’s displacement?
What is the gecko’s displacement in Figure 2?

7. Displacement vs. Distance
If the gecko in Figure 2 traveled from the 24.5 cm mark to the 85.5 cm mark
Displacement = 61.0 cm and Distance = 61.0cm
BUT
If the gecko traveled from the 24.5 cm to the 85.5 cm, and returned back to the 24.5 cm mark
Displacement = 0 and Distance = cm

8. Round trips
If you return to the starting point (round trips) the displacement will always be = 0.
Displacement is: How far away you are from where you started.

9. What is the runners Displacement? Distance?

10. Displacement can be + or (-)
See Table 1 on Page 42
To the right , east, upward, or north = Positive
To the left, west, downward, or south = Negative

11. Velocity is speed in
a given direction

12. Vavg = Δx (xf – xi)
Δt (tf – ti)
**ADD formula to your index card

13. Units Displacement – SI unit for length is meters
Time – SI Unit for time is seconds
(Velocity) – SI unit is m/s.

14. Units
**Since displacement can be either positive or negative, velocity has to have a direction on your answers; indicating the direction in which the object is traveling.

15. CLASSWORK
PAGE 44 #’S 1-6

16. BELLWORK 9/12/17 Round your answers using the rules for sig figs.
( ) / 12 =

17. Vectors and Scalar Quantities
The motion of objects can be described by words. Even a person without a background in physics has a collection of words that can be used to describe moving objects. Words and phrases such as going fast, stopped, slowing down, speeding up, and turning provide a sufficient vocabulary for describing the motion of objects.

18. Vectors vs. Scalars (cont)
In physics, we use these words and many more. We will be expanding upon this vocabulary list with words such as distance, displacement, speed, velocity, and acceleration. As we will soon see, these words are associated with mathematical quantities that have strict definitions.

19. Vectors vs. Scalars (cont)
The mathematical quantities that are used to describe the motion of objects can be divided into two categories. The quantity is either a vector or a scalar. These two categories can be distinguished from one another by their distinct definitions:

20. Vectors vs. Scalars
Scalars are quantities that are fully described by a magnitude (or numerical value) alone.
Vectors are quantities that are fully described by both a magnitude and a direction

21. Vectors vs. Scalars
Velocity is a vector quantity that has a magnitude (numerical value) and a direction.
Speed has no direction (scalar quantity)
Displacement is a vector quantity that has a magnitude and a direction.
Distance is a scalar quantity (no direction)

22. Checkpoint 5m 30m/s, east 5 mi, north 20 degrees celsius 256 bytes
4000 calories
Vector or Scalar

23. Checkpoint Answers 5m 30m/s, east 5 mi, north 20 degrees celsius
256 bytes
4000 calories
Scalar
Vector, has a direction
Vector; has a direction

24. Speed vs. Velocity
Just as distance and displacement have distinctly different meanings (despite their similarities), so do speed and velocity.
Speed is a scalar quantity that refers to how fast an object is moving.
Speed can be thought of as the rate at which an object covers distance.

25. Speed
Formula: speed = distance
time

26. Velocity is a Vector Quantity
Velocity is a vector quantity that refers to the rate at which an object changes its position.
Imagine a person moving rapidly – one step forward and one step back- always returning to the original starting position.
This activity would result in a zero velocity, because the displacement is zero.

27. Velocity
Formula: Vavg = displacement
time

28. Direction of Velocity
The direction of the velocity of an object is simply the same as the direction in which the object is moving.

29. CHECKPOINT
While on vacation, Jamie traveled a total distance of 440 miles. Her trip took 8 hours, what was her average speed?

30. ANSWER Speed avg = distance time Speed avg = 440 mi 8 hrs
This was just her average speed. She may have been traveling 70 mi/hr at some points, or she may have even stopped for food.

31. Average Speed vs. Instantaneous Speed
Since a moving object often changes its speed during its motion, it is common to distinguish between the average speed and the instantaneous speed. The distinction is as follows.
Instantaneous Speed - the speed at any given instant in time.
Average Speed - the average of all instantaneous speeds; found simply by a distance/time ratio.

32. Instantaneous Velocity can be calculated graphically
The instantaneous velocity at a given time can be determined by measuring the slope of the line that is tangent to that point on the p-t graph.

33. Turn to Page 46
Look at Figure 7 and copy the graph on a sheet of graph paper.
Show how the instantaneous velocity is 12 m/s.

34. SUMMARY What is the difference between a vector and a scalar quantity?
What is the difference between distance and displacement? Which one is a vector quantity?
What is the difference between speed and velocity? Which one is a vector quantity?
What is the formula for average speed?
average velocity?

35. Pre-Lab – Physics 400 Find a Lab group of 4 Read the lab
Work on Step #2
Construct your data table