Review
­
velocity
­
how to calculate velocity
­
how velocity is different then speed
­
using the velocity formula
Feb 18­11:28 AM
Review graphs covered:
­
distance/ time graph
­
speed/ time graph
­
what these graphs indicate
Feb 18­11:30 AM
1
Position Time Graph
­ a graph in which position is plotted on the
axis and time is plotted on the x­axis
­
y­
the vector quantity of position is used
Ex.
Position Time Graph for John walking
East of his house
Feb 18­11:31 AM
Distance Time Graph vs Position Time Graph
Bob walks to his friends house and back
Why are the graphs different shapes?
See graphs on page 447 and discuss why they are shaped like they are?
Feb 18­11:37 AM
2
Slope of a Graph
­ slope is the steepness of a line expressed as a relationship of two variables: rise and run
­ rise: height along the y axis
­ run: length along the x axis
­
slope is expressed as a mathematical formula
Slope = rise
run
Feb 19­10:08 AM
­ slope can be applied to distance­time graphs and position­time graphs
­ for Distance­Time Graphs slope expressed as:
Slope = rise
run
or
distance
time
­ the slope will indicate the speed at a particular point of the graph
­ the slope of a distance­time graph will always be positive
Feb 19­10:12 AM
3
Feb 19­10:25 AM
Feb 19­10:24 AM
4
­
slope of a Position­Time Graph is expressed as:
Slope = rise
run
or
displacement
time
­ the slope will give velocity at a particular point
­ this slope can be expressed as a positive or a negative (Why?)
Feb 19­10:14 AM
Feb 19­10:24 AM
5
Feb 19­10:31 AM
Instantaneous Velocity
­
change in position over an extremely short period of time (like instantaneous speed plus a direction)
­
this is used when you have an object that is accelerating, not a constant velocity (the graph will be curved)
See Sample Problem 2 on page 449
Feb 19­10:17 AM
6
Readings:
Pages 446 ­ 449
Problems:
Page 450: #'s 1,2,3,4,6,7
Feb 19­10:21 AM
7