Describing Motion

1
Describing Motion
Chapter 9.1 Page 338
2
Objectives for 9.1

• Know how to determine if an object is in motion.
• Know what a reference point is.
• Explain how objects can have different speeds
  depending on the reference point.

3
What is Motion?

• An object is in motion when its distance from
  another object is changing.

4
Reference Points

• To determine if something is in motion, you need
  a reference point.
• Reference Point a place or object used for
  comparison to determine if something is in motion.

5
Relative Motion

• Relative motion is the speed you are traveling in
  comparison to a specific reference point.
• Are you moving?
• With reference to your chair 0 mph
• With reference to the moon 820 mph
• With reference to the sun 67,000 mph

6
Describing Distance

• Distance is the length of a path between two
  points
• The SI unit of length to be used depends on the
  size of the object being measured.
• Long Distances are measured in Kilometers (km)
• Large objects are measured in meters (m)
• Small objects are measured in centimeters (cm)
• Very small objects are measured in millimeters
  (mm)

7
Distance and Displacement

• Distance is the total length of the actual path
  between two points.
• Displacement is the length and direction of a
  straight line between starting and ending points.

8
Vectors

• A vector is a visible way (an arrow) to show the
  magnitude (amount) and direction of a quantity.

Same direction, Different magnitude
Same magnitude, Different direction