In Thought Think of how you arrived to school today. Did
you walk, drive, take the bus? Write a paragraph describing how you got to school.
Great words to include in your paragraph:MotionSpeedAccelerationReference pointPosition
ObjectivesExplain when an object is in motion and how
motion is relative to a reference pointCalculate an object’s speed and velocity
using SI units of distanceGraph motion showing changes in distance as
a function of time
Recognizing MotionHow would you describe an object in motionAn object is in motion when its distance from
another object is changingTo determine if something is in motion you need a
reference pointIf an object is moving at the same rate of speed as
you the object does not appear to be movingThe walls in your classroom do not appear to be
moving because they are moving at the same rate of speed as you
Earth is moving at 30 km per second – LA to NY is 2 min
Reference PointReference point is a place or object used for
comparison to determine if something is in motion
An object is in motion if it changes position relative to a reference point
Position is an object’s distance and direction from a reference point
Using Reference Points At a school you may describe your position
compared to a hallway – ie “I am standing outside the 800’s.”
Direction is often used with a reference point “I am a block east of the train station.”
Reference point
Reference Point
Reference PointWhich one is in motion? How can you tell?
Can the other 2 be in motion?
Using Reference Points Describe the location of the yellow car from our vantage point.
Above the asphalt
To the right of the lead car.
To the left of the Texaco and Home Depot cars.
Describing Distance International System of Units (SI system)The basic SI unit of length is the meter
(metre)Meter is roughly 39 inchesDistance is how far two objects are from one
anotherSmaller Units of Distance
Larger Units of Distance
Deci = 1/10 of a meter Deka = 10 meters
Centi = 1/100 of a meter
Hecto = 100 meters
Milli = 1/1000 of a meter
Kilo = 1000 meters
Calculating SpeedSpeed of an object is the distance the object
travels in one unit of timeSpeed is a rate A rate tells you the amount of something that
occurs or changes in one unit of timeSpeed = unit of distance / unit of time
SPEED = DISTANCE / TIMEUsually speed is measured in m/s or km/h
Types of Speed Constant speed – is the rate of change in which
the same distance is traveled each second Instantaneous speed – is speed at a given instant
of timeAverage speed – is the total distance traveled
divided by the total time taken to travel that distance
v= d/t v equals average velocity d equals distancet equals time
What type of speed is shown in each picture?
Instantaneous Speed
Cruise Control
Constant Speed
Time from
Pt A to Pt B
Average Speed
Speed at this point
Instantaneous speed
DisplacementDisplacement (s) – is the shortest distance
between two places/objectsShortest distance is a straight line s = final position of a point – the initial
position of a pointDisplacement formula s = Rf – Ri = ΔR
A
B
Graphing Motion On a line graph plot distance against timeTime is placed on the horizontal or x-axisDistance is placed on the vertical or y-axisSlope is the steepness, or slant, of a line on a
graph
ReviewSpeed is distance divided by timeVarious speeds include constant,
instantaneous and average speedUse a reference point to determine motionVelocity is speed in a given direction