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Motion
Distance, Displacement Speed,
Velocity, and Acceleration
Tools to Describe Motion
Language (Text) Diagrams and Maps (Figures) Measurements (Variables) Tables, Graphs and Charts
(Organizers) Equations (Mathematics)
Distance (d) & Displacement (∆x) Is a measure of the
length of the path of a moving object.
Is a scalar, since it has no direction.
Units: Meters
Is a change in position of the object and is a measure of the direct distance from start to finish .
Is a vector, since it has direction.
if xxx
Motion Motion is a change in position
relative to a frame of reference Speed is the distance traveled
in a given amount of time
Time
ceDisSpeed
tan
t
xx
t
dv if
Types of Speed Constant Speed: Is
when speed stays the same. The ratio of d/t is always constant.
Changing Speed: Is when speed changes, the ratio d/t is not a constant
Instantaneous Speed: Is the speed at that moment. Ex. Speedometer reading.
Average Speed: Is total distance / time
Units for Speed
The units for speed: meters/second (m/sec) kilometers/hour (km/hr) Miles per hour (mph) is a
non metric unit of speed.
Average speed
Total distance divided by the total time
Formula:
t
x
TotalTime
ceTotalDisedAverageSpe
tan
Velocity Speed in a given direction Velocities in the same direction
combine by adding Velocities in different
directions combine by subtracting
Interesting facts
Rockets are launched in the same direction of the earth’s rotation to get an extra boost of 1800 km/hr to its speed
Likewise airplanes takeoff in the direction of the wind and land against the wind.
Questions (Bell ringer)
What is a frame of reference?
Why do we call it so? What is the most common
frame of reference? What is the frame of
reference for the sunset?
Frames of Reference (Answers) It is the object or point from which
movement is determined. Since movement is relative to an
object that appears to be stationary.
Earth is the most common frame of reference.
The earth.
Questions (Bellringer) What is motion? What is speed? How is it calculated?
What is average speed?
Questions (Bellringer)
How is velocity different from speed?
Which two factors determine an object’s velocity?
Acceleration The change in velocity Acceleration is measured in
m/sec/sec or m/sec2
Formula is: (final velocity - original
velocity)/time
t
vva if
Deceleration vs. Acceleration A decrease in velocity is
deceleration NOT negative acceleration, which is acceleration in the negative direction.
A distance-time graph for acceleration is always a curve
Centripetal Acceleration
Acceleration directed toward the center of circular path
Questions What is acceleration? What is the shape of a
distance-time graph for acceleration?
What is centripetal acceleration?
Momentum Momentum is equal to the mass of an object times its velocity
momentum= mass x velocity
Conserving Momentum The law of conservation of momentum states that the total momentum is NOT lost, only transferred
Questions What is momentum? What happens to momentum
as the mass of a moving object increases?
What is the formula for momentum?
What is the law of conservation of momentum?