Transcript Lesson 20 - Acceleration

Acceleration
Science 10
Constant Velocity Problems
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2.
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10.
54km/h
612km/h
5.3km/h
420km
3.64h
7.5h
3000km
12km
8.20m/s
6.5km/h
11.
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20.
36000km
45s
9.49m/s
465km
1.49x108km
.0909h
12m
330m/s
3.3x10-7s
.450s
Acceleration
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When an object’s velocity changes,
we refer to that as acceleration
Speed/velocity is the rate of change
of position and is typically measured
in m/s
Acceleration is the rate of change of
velocity/speed and is typically
measured in m/s2
A Dropped Object
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Plot the following
points on a
position time graph
Connect the points
with a smooth
curve (not a series
of straight lines)
How can you
measure the speed
of the object at
any point?
time (s)
0
0.1
0.2
0.3
0.4
0.5
0.6
height (m)
2
1.95
1.80
1.55
1.21
0.77
0.23
Tangent Line
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A tangent line is a
straight line that
touches a curve at
only one point
If you draw a
tangent line and
calculate the slope,
you have the
instantaneous
velocity/speed of
the object
Instantaneous Velocity
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Using your position time graph, draw
a tangent line at 0s, .25s and .5s
Calculate the slope of each of these
tangent lines
Draw a new graph with velocity on
the y-axis (m/s) and time (s) on the
x-axis
Plot your three points on the velocity
time graph; what do you notice?
Acceleration
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A straight line on a velocity time
graph indicates constant acceleration
and the slope of the line is the
measure of the acceleration
Does the slope of the line on your
velocity time graph appear similar to
any numbers we have seen in the
past?
Acceleration due to Gravity
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In the lab we measured the
acceleration due to gravity and
compared it to the accepted value
(9.81m/s2)
The data you plotted here is also for
an object dropped (from a height of
2.00m) so the slope of the line on
the velocity time graph should
compare favourably to this number