Motion is relative An objects motion is always described in reference to another object Relative Motion When an object is said to be traveling at 60 km h or at any speed it is implied that it is moving at 60 kmh relative to the Earth ID: 602125
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Slide1
Linear MotionSlide2
Motion is relative
An object’s motion is always described in reference to another object
Relative MotionSlide3
When an object is said to be traveling at 60 km/
h (or at any speed),
it is implied that it is moving at 60 km/h relative to the Earth.
Relative MotionSlide4
Jamiroquai
“Virtual Insanity”
Travelling Without Moving
1997 Video of the Year
Relative Motion
CLICK HERE TO WATCH THE VIDEO!Slide5
Vector- a quantity possessing both magnitude and direction
Scalar- a quantity possessing only magnitude
Vectors and ScalarsSlide6
Examples of Vectors:
Displacement (
Δ
x)
Velocity (v)
Acceleration (a)
Force (F)Momentum (p)
Vectors and ScalarsSlide7
Examples of Scalars:
Distance (d)
Mass (m)
Speed (v)
Time (t)
Vectors and ScalarsSlide8
Instantaneous speed: the speed that something has at any one instance
Average speed: the speed of an object over a time interval
SpeedSlide9
Speed
The
average speed
for a trip might be 53 miles/hour.
...or 70 miles/hour on the open road.
However, during this trip your
instantaneous speed
might have been 0 miles/hour at a stoplight... Slide10
Speed
What are the
units
of speed?
miles/hour…………….mph
kilometer/hour……….km/h
meters/second……….m/s
furlongs/fortnight?Slide11
Speed
1. What is the average speed of a cheetah that sprints 100 meters in 4 seconds?
2. How about if it sprints 50 m in 2 s?Slide12
Velocity
Velocity
= {speed with a direction}
Examples:
70 mph
is a
speed
.
70 mph North
is a
velocity
.Slide13
Velocity
What are the
units
of velocity?
Velocity has the same units as speed except they also have a directionSlide14
Velocity and speed equationsSlide15
Velocity vs. speed
The speedometer of a car moving to the east reads 100km/h. It passes another car that moves to the west at 100km/h.
Do both cars have the same speed?
Do they have the same velocity?Slide16
In an unusual move by the New York State Department of Transportation, all of the "speed limit" signs were replaced with "velocity limit" signs.
What would such a sign look like?
How could one travel faster than the old speed limit without violating the new velocity limit?
Conceptual ReviewSlide17
Which device(s) on a car can be used to change …
its speed?
its velocity but
not
its speed?
Conceptual ReviewSlide18
A car driving on a circular test track shows a constant speedometer reading of 100 kph for one lap.
Describe the car's speed during this time.
Describe its velocity.
How do the speed and velocity compare?
Conceptual ReviewSlide19
Is it possible for an object to have …
constant speed and changing velocity,
changing speed and constant velocity?
Conceptual ReviewSlide20
Why are the devices in cars called speedometers and not velocitometers?
Conceptual ReviewSlide21
OK Go
“Here It Goes Again”
Oh No
2007 Grammy award for "Best Short-Form Music Video”
Relative Motion
…one more time
CLICK HERE TO WATCH THE VIDEOSlide22
Acceleration
Acceleration is the rate of change of velocity.Slide23
Acceleration
What are the
units
of acceleration?
miles/hour/second…………….mi/h/s
kilometer/hour/second……….km/h/s
meters/second/second……….
m/s/s or m/s
2Slide24
Acceleration equationsSlide25
Acceleration
Acceleration is the
positive or negative depending on the direction of the acceleration.Slide26
Acceleration
An object traveling with a constant positive velocity Slide27
Acceleration
An object traveling with a constant negative velocity Slide28
Acceleration
An object traveling with a positive velocity, positive acceleration. Slide29
Acceleration
An object traveling with a positive velocity, negative acceleration. Slide30
Acceleration
An object traveling with a negative velocity, negative acceleration. Slide31
Acceleration
An object traveling with a negative velocity, positive acceleration. Slide32
Graphs of Motion
O
n a
displacement vs. time
graph the slope of the line is equal to the
velocity
of the object.
O
n a
velocity vs. time
graph the slope of the line is equal to the
acceleration
of the object.
O
n a
velocity vs. time
graph the area underneath the curve is equal to the
displacement
of the object.