Rate of Change
What is it?
 A slope is the rate at which the y changes as the x
changes
 Velocity is the rate the position of an object changes
as time changes, therefore it is the slope of a position
versus time graph
 If the graph is not a straight line, the velocity at a
single point is the slope of the tangent line to that
point – called Instantaneous Velocity
Example
 Suppose a ball is dropped from the deck of the CN
Tower, 450 meters above ground. If its position (s) at
a given time (t) is given by the function s = 4.9 t2
a) what is the velocity after 5 seconds?
b) how fast will the ball be travelling when it hits the
ground?