# Picturing Motion Dot Diagrams by vhd10964

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```									    Picturing Motion: Dot Diagrams

• If you related the position of the runner to the background in each
frame taken in 1 second intervals, you would conclude that the student
is in motion.

• This series of images, taken at regular intervals, creates a motion
diagram for the change in the student’s state of motion.
• Roll a ball along a horizontal
surface, and its velocity is
constant because no component
of gravitational force acts
horizontally
• Drop it, and it accelerates
downward and covers greater
vertical distances each second.
By noting the distance the object moves in
equal time intervals, you can determine the
object’s state of motion
• A: at rest
• B: moving at a
constant speed
• C: speeding up
• D: slowing down.
Use a dot motion diagram model to draw simplified
motion diagrams

• A: at rest
• B: moving at a
constant speed
• C: speeding up
• D: slowing down.
• Use the dot diagram model to draw a
motion diagram for an object moving at a
constant speed.

• Use the dot diagram model to draw a
motion diagram for an object starting at
rest and speeding up.

• Use the dot diagram model to draw a
motion diagram for an object that starts
from rest, speeds up to a constant speed,
and then slows to a stop.
• Use the dot diagram model to draw a
motion diagram for a wheel turning at a
constant speed. First place the dot at the
hub of the wheel. What would the diagram
look like if the dot were placed on the rim
of the wheel?
Dot Diagrams & Vector Quantities
• To determine displacement, velocity, and
acceleration, a coordinate system must be
specified.
• Normally the positive values of x extend
horizontally to the right, and the positive
values of y extend vertically upward.
• The sign of the average velocity depends
upon the chosen coordinate system. The
coordinate systems in a and b are equally
correct
• Color Conventions
– Displacement vectors are green.
– Velocity vectors are red.
– Accelerations vectors are violet
Graphs and motion diagrams are useful in
differentiating constant motion and motion
that is accelerated.
• A speed-versus-time graph
• A distance-versus-time graph
• The sign of the acceleration depends upon
the chosen coordinate system.
• Ex: a ball being rolled up an inclined driveway
+
Freefall
• The rate at which the velocity
changes each second is the
same whether the ball is going
upward or downward.

-
    Refer to the motion graph below to find
1.   The time interval(s) for positive acceleration
2.   The time interval(s) for negative acceleration
3.   The time interval(s) for constant velocity
4.   The time interval(s) for zero acceleration
5.   At what time(s) does the car appear to be at rest?
6.   At what time(s) does the car turn around and
move in the opposite direction?

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