Chapter 1: Motion Section 1: Describing and Measuring Motion How do you recognize motion?

1
Chapter 1 MotionSection 1 Describing and
Measuring MotionHow do you recognize motion?

• An object is in motion when its distance from
  another object is changing
• Movement depends on your point of view

2
What is a reference point?

• 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

3
What is the basic unit of length?

• The meter a little longer than a yard

4
What do scientists use to measure the length of
an object smaller than a yard?

• A centimeter one hundredth of a meter, so there
  are 100 centimeters in a meter
• A millimeter There are 1,000 millimeters in a
  meter

5
How do scientists measure long distances?

• The kilometer There are 1,000 meters in a
  kilometer

6
How do scientists calculate speed?

• Speed the distance the object travels in one
  unit of time
• Rate tells you the amount of something that
  occurs or changes in one unit of time
• Speed distance
• time

7
What is constant speed?

• If the speed of an object does not change, the
  object is traveling at a constant speed

8
What is average speed?

• Most objects do not move at constant speeds for
  very long
• To find average speed divide the total distance
  by the total time

• Car trip

9
What is Velocity?

• Speed in a given direction
• When you know the speed and direction of an
  objects motion, you know the velocity of the
  object
• Example 15 km/hour westward

10
How do you graph motion?

• You can show the motion of an object on a line
  graph in which you plot distance against time
• Time is along the x-axis and distance on the
  y-axis

11
How do you interpret motion graphs?

• A straight line indicates a constant speed
• The steepness depends on how quickly or slowly
  the object is moving
• The faster the motion the steeper the slope

12
Section 2 Slow motion on Planet Earth

• According to their explanation, known as the
  theory of plate tectonics, Earths plates move
  ever so slowly in various directions

13
How fast do plates move?

• Some small plates can move as much as several
  centimeters per year, whereas other move only a
  few millimeters per year

14
How can you calculate the distance an object has
moved?

• Rearrange the speed formula
• Distance Speed x Time
• Converting units choose a conversion factor
  that will allow you to cancel units

15
Section 3 AccelerationWhat is Acceleration?

• The rate at which velocity changes
• In science, acceleration refers to
• increasing speed
• decreasing speed
• changing direction

16
How do you calculate acceleration?

• To determine the acceleration rate of an object,
  you must calculate the change in velocity during
  each unit of time
• Acceleration Final velocity Initial velocity
• Time

17
How do you interpret graphs to determine
acceleration?
Acceleration vs. Constant speed

• The acceleration at any moment is equal to the
  slope of the velocity time graph at that moment
  in time

18
(No Transcript)
19
(No Transcript)
20
(No Transcript)