Describing and Measuring MOTION

1
Describing and Measuring MOTION

• Section 1.1 Notes

2
Key Concepts

• When is an object in motion?
• How do you know an objects speed and velocity?
• How can you graph motion?

3
Describing Motion

• You are in MOTION if your distance from another
  object is changing
• Depends on a REFERENCE POINT
• Place or object used for comparison

4
Describing Motion

• Are you moving?
• Reference point SMARTboard
• Ref. pt. Sun
• To determine motion, you must know your reference
  point!!

5
Relative Motion

• Motion is relative to your reference point.
• Questions
• On the next slide, are the skydivers moving
  relative to each other?
• Are they moving relative to the airplane from
  which they jumped?
• Are they moving relative to the ground?

6
Relative Motion
Boat example people in boat compared to shore
why? people in boat compared to boat why?
7
Measuring Distance

• You use units of measurement to describe motion
• SI System is used to describe the distance an
  object moves.
• Meter basic measurement for length

8
Review

• How many cm in a m?
• 100 centimeters in a meter
• How many mm in a m?
• 1000 millimeters in a meter
• How many m in a km?
• 1000 meters in a kilometer

9
Converting Units
- Describing and Measuring Motion

• Practice Problem
• How many centimeters are in 22.5 meters?
• HINT Multiply length by 100.
• 22.5 m 2,250 cm

10
SPEED

• The distance an object moves in a certain amount
  of time
• Speed distance / time
• Units depend on measures of distance and time
• m/s km/h m/h

11
Average Speed

• Overall speed of an object
• Calculate by dividing total distance by total
  time

12
Instantaneous Speed

• Rate at which an object is moving at a given
  instant in time.
• Why is the
• instantaneous speed
• different from the
• average speed?

13

• Question Would a radar gun (used by police
  officers) measure
• average speed
• or
• instantaneous speed?
• WHY?
• Answer Instantaneous speed

14
VELOCITY

• Speed in a given direction.
• You need to know the direction to know velocity
• Important to pilots, weather forecasters, air
  traffic controllers

15
Graphing motion!!

• Motion graphs plot distance versus time
• Slope rise/run
• Slope distance/time
• Slope speed of that segment

16
Graphing Motion
17
Converting Units
- Describing and Measuring Motion

• Use a conversion factor to convert one metric
  unit to another. A conversion factor is a
  fraction in which the numerator and denominator
  represent equal amounts in different units.
  Multiply the number you want to convert by the
  conversion factor.
• Suppose you want to know how many millimeters
  (mm) are in 15.5 meters (m). Since there are
  1,000 millimeters in 1 meter, the conversion
  factor is
• 1,000 mm/1 m
• Multiply 14.5 meters by the conversion factor to
  find millimeters.
• 14.5 m X 1,000 mm/1 m
• 14.5 X 1,000 mm
• 14,500 mm

18
(No Transcript)
19
Graphing Motion Activity
- Describing and Measuring Motion

• Cgp - 3011