topic: position-time graphs unit 1: chapter 1 and 2
TRANSCRIPT
Topic:Position-Time
GraphsUnit 1: Chapter 1 and 2
What do patterns in data show us?
• Patterns in data allow us to see relationships between variables
• Graphing data provides a visual image of the relationships between variables in a set of data
Strong pattern = Strong relationship Weak/no pattern = no relationship
How do graphs show strong and weak relationships? • Strong relationship• Small change in one variable
makes a big change in another
• Weak relationship• Changes in one variable has little
to no effect on the other variable
How do we represent motion with a graph?• The motion of an object can be
represented by a position-time graph
• Definition:• Position-time graphs show where things
are at different times
• X-axis:• Represents time
• Y-axis:• Represents position relative to the
starting point
Why are position-time graphs useful?• Suppose you take a car trip that includes 1.5 hours of driving and a half-
hour rest stop, for a total time of 2 hours. You drive a total distance of 90 miles in a straight line. What is your average speed?• 90 miles/2hours = 45mph
• Did you really drive for 2 hours without stopping?• No
• You really covered the 90 miles in 1.5 hours at a speed of 60mph and stopped (with zero speed) for a half hour
Figuring out velocity from a position-time graph• In a position-time graph the velocity of an object can be calculated
using the slope of the graph line
• Steeper line = greater slope = faster the object’s motion
• Slope = average velocity of the object
How do you calculate slope?
• Slope equation
• Using the slope equation:• Pick two points on the line and determine their coordinates• Determine the difference in y-coordinates of these two points (rise)• Determine the difference in x-coordinates of these two pointes (run)• Divide the difference in y-coordinates by the difference in x-coordinates