Post on 23-Feb-2016
description
Why go into physics? Go to www.physics.orgFind 3 areas that interest youList 2 jobs that you could have in
that areaGoogle 1 of the jobs and try and
find out how much that job makes
Physics effects every moment of your life! ____________________________________________________________________________________________________
CH. 2 Motion Keep on truckin
What is motion? Motion is a change of position of an
object. A reference point must be specified in
order to determine an object's position
What is Speed? Rate—any change over timeSpeed—the distance an object
travels per unit of time.
fastest
Graphs! Speed= distance time graphs
The slope of a line (steepness) on a distance-time graph is equal to the speed. Shallow slope is slower than steep slope
The Comic Book of Science
Draw this on your paper!
slower
faster
Time (seconds)
Dist
ance
(m
eter
s)
Standing stillX-axis
Y-axis
Distance Time GraphsWhat information is
recorded on the x-axis?
How many minutes does each line represent?
In what units is distance measured on the graph?
The graphs represent three swimmers, What does the slope of the lines tell you about the swimmers?
Which swimmer swam the fastest?
Which swimmer stopped for 10 minutes?
How far did the blue swimmer travel in 15 minutes?
What is the difference in distance traveled between the red and green swimmer?
Warm-up 1/31/11Review questions: What is one
thing that is good for the brain to learn?
Teach the teacher questions: What is your favorite dessert?
Do you have a cell phone? Does your cell phone have a camera?
What are the fastest animals (mph)?Cheetah 70Pronghorn antelope 61 Lion 50 Thomson's gazelle 50 Wildebeest 50 Springbok 50 Quarter horse 47.5 Cape hunting dog 45 Elk 45 Coyote 43
Calculating Speed• The speed of an object can be
calculated from this equation: Speed = Distance Time
S=D/T
When working equations◦Write the formula◦Plug in the values for each known◦Calculate the answer◦Write the answer and a unit
D
S T
multiply
divide
Average & Instantaneous SpeedAverage speed—the total distance traveled divided by the total time of travel.
Instantaneous speed—the speed at a given point in time.
VelocitySpeed describes
only how fast something is moving.
Velocity—includes the speed of an object AND the direction of its motion
Example: Example: a race
car has a constant speed of 100km/hr around an oval track.◦The speed remains constant, but the velocity changes.
AccelerationAcceleration—the rate of change of
velocity.◦The change in velocity over time◦acceleration = change in velocity
timeWhen something speeds up, it has a
positive accelerationWhen something slows down, it has
a negative acceleration.