Do Now for 4/15/13
Open Books up to activity E75
HW: None
E75: Interpreting Motion Graphs
• Today’s Target: I will be able to see how a
graph can be used to describe the motion of
an object.
• Binder clean out and grade evaluation
• Introduce and write up E75
• Complete procedure
• Clean up
• Analysis?
Binder Clean Out
• Keep:
– General Information
– Vocabulary
– E Unit Materials
• Complete grade evaluation sheet
– Did you earn extra credit???
E75: Interpreting Motion Graphs
• We measured the speed of carts in activity 74.
• Were the carts always traveling at the same
speed?
• Do you travel at the same speed for your entire
trip to school?
• Do you always travel in the same direction in
your trip to school?
• We can use a graph to visualize the trip of
someone traveling to and from school.
E75: Interpreting Motion Graphs
•
Where is the
length of
time located?
Where is
distance
traveled
located?
What do you
think this part of
the graph
means?
What do you
think this
part of the
graph
means?
What do you
think this part of
the graph
means?
One square
per person.
Do Now for 4/16/13
• Take out E75
• HW: Expanded answer for question #2 due
TOMORROW!!
• Today’s Target: I will be able to see how a graph
can be used to describe the motion of an object.
• Complete graphing data – Make sure you
include reasons why you put the strips where
you did!
• Go over data
• Analysis 1 through 5
• Key Points
• Expanded answer for #2
E75: Interpreting Motion Graphs
• 1. Identify a place on each graph where the
slope of the line changes. What does a change
in the slope of a motion graph indicate?
– A change in slope indicates a change in the
distance traveled in a given time, which is defined
as speed.
E75: Interpreting Motion Graphs
• 2. Which student –Teasha or Josh– started out
faster? Explain how you know this.
• Expanded Answer
– Correctly state who started out faster.
– Give at least two (2) pieces of evidence from the
graph to support your answer.
– Due tomorrow.
E75: Interpreting Motion Graphs
• 3. How far into the trip did Josh turn around?
Describe what the graph looks like at this point in
the trip.
– Josh turned around 6 minutes after he left home—5
minutes traveling 2 miles and 1 minute stopped. You
know this because from Minute 6 to Minute 10, the
slope of the graph is negative(downward), which
indicates a reversal in the direction of motion. With a
positive (upward) slope, the distance away from the
starting point increases with time. With a negative
slope, distance from the starting point decreases with
time, which means that the car is getting closer, or
traveling back toward, the starting position.
E75: Interpreting Motion Graphs
• 4. Look at the motion graphs shown on page E-14. Match the
descriptions here to the correct graphs:
• a. A car moving at a constant speed stops and then moves in the
opposite direction at the same speed.
– Graph 2
• b. A car moving at a constant speed stops and then moves faster in
the same direction.
– Graph 4
• c. A car moving at a constant speed changes to a higher constant
speed.
– Graph 1
• d. A car moving at a constant speed changes to a lower constant
speed.
– Graph 3
E75: Interpreting Motion Graphs
• 5. A car that accelerates (ak-SELL-ur-ates) is one
that speeds up, slows down, or changes direction.
Which graph on page E-15 shows a car
continually accelerating? Explain how the shape
of the graph shape shows this.
– Graph A (on the left) shows an object accelerating.
This is because it has a curved line that shows
increasing steepness in slope as time increases. Graph
B (on the right), in contrast, has a constant slope so it
shows constant speed. Both graphs show motion in a
straight line.
E75: Interpreting Motion Graphs –
Key Points
• 1. The motion of an object can be describe by
its position, direction of motion, and speed.
• 2. Motion can be measured and represented
on a graph.
• 3. Average speed is the distance an object
travels divided by the time taken to travel that
distance.
• 4. Mathematics is important in all aspects of
scientific inquiry.
E75: Interpreting Motion Graphs
• 2. Which student –Teasha or Josh– started out faster?
Explain how you know this.
– Teasha started out faster. This can be determined several ways:
– 1) The trip strip for Teasha’s first segment states that the car
traveled 3 miles in 6 minutes. Using the formula s = d/t, this is a
speed of 0.5 miles/minute. The trip strip for Josh’s first segment
states that the car traveled 2 miles in the first 5 minutes. Using
the formula s = d/t, this is a speed of 0.4 miles/minute.
– 2) The trip strip for Teasha’s first segment states that the car
traveled 3 miles in 6 minutes. Since Josh did not travel as far in
the same amount of time, Tesha must have been traveling
faster.
– 3) The first segment of Teasha’s graph has a steeper slope than
the first segment of Josh’s graph. A steeper line (higher value for
slope) indicates a higher speed.