Foundations of Physical Science

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Foundations of Physical Science

• Unit One Forces and Motion

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Chapter 1 Science and Measurement

• 1.1 Time and Distance
• 1.2 Investigations and Experiments
• 1.3 Speed

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Learning Goals

• Accurately measure time using electronic timers
  and photogates.
• Use decimals to represent fractions of a second.
• Develop a research question or hypothesis that
  can be tested.
• Identify the variables that affect motion.
• Develop an experimental technique that achieves
  consistent results.

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Learning Goals (continued)

• Draw conclusions from experimental results.
• Accurately measure distance.
• Identify metric and English units of distance.
• Convert between units of distance.
• Calculate speed in units of inches per second,
  feet per second, and centimeters per second.

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Vocabulary

• cause and effect
• controlled experiment
• controlled variables
• distance
• English system
• experiment
• experimental technique
• experimental variable
• hypothesis
• investigation
• length

• measurement
• metric system
• procedure
• research question
• scientific evidence
• scientific method
• second
• time
• trial
• variables

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1.1 Time and Distance
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Two Ways to Think about Time

• What time is it?
• How much time?

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How is Time Measured?

• Time comes in mixed units.
• Seconds are very short.
• Hours and minutes are more convenient for
  everyday time measurement.

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Electronic Timers

• Have displays that show mixed units.
• To read a timer you need to recognize and
  separate out the different units.
• Colons () separate the units.

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Measuring Distance

• Describes how far it is from one point to another
• Measured in units of length
• Two common systems of units
• English (inches, feet, miles)
• Metric (millimeters, centimeters, meters,
  kilometers)

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Measurement and the English System
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Measurement and the Metric System
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Measurement

• Units were invented so people could communicate
  amounts to each other.

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1.2 Investigations and Experiments
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Designing Experiments

• How do we ask questions and get answers from
  nature?

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Experiment

• Any situation we set up to observe what happens.
• In science, we usually plan our experiments to
  give us measurements, which are observations we
  can record and think about.
• Experiments have questions associated with them.
• Experiments are the way we ask questions of
  nature.

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Scientific Method

• Developed by Galileo and the English philosopher
  Francis Bacon in the 16th century
• Based on rational thinking and experimentation

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Designing Experiments

• Start with a good question
• Identify all the factors when designing
  experiments
• Variables
• Change one thing at a time
• Control variables and experimental variables

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Hypothesis

• An educated guess about what will happen

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Experimental Techniques

• Experiments often have several trials
• Experimental technique
• Procedures
• Scientific results must always be repeatable

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Limitations

• Science deals only with hypotheses that are
  testable
• Science is restricted to the observable natural
  world
• Supernatural above nature cannot be explained
• Philosophical questions cannot be answered

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Pseudoscience

• Some belief systems are not science but pretend
  to be
• Phrenology the study of the surface bumps on a
  persons head to identify health and personality

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Pseudoscience

• Astrology the study of the stars and planets and
  their movements as well as their affects on the
  lives and behavior of human beings

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The Search For Order

• Science
• Art
• Religion

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Technology

• Practical use of the findings of science
• Science concerned with gathering knowledge and
  organizing it
• Technology lets humans use that knowledge for
  practical purposes, and it provides the
  instruments scientists need to conduct their
  investigations

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Technology

• Can be helpful and can be harmful
• Example find fossil fuels used in countless ways
  while damaging the environment
• Technology is our tool to fix these problems

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The Sciences

• Life Sciences biology, zoology, botany, etc.
• Physical Sciences physics, chemistry, gemology,
  meteorology, astronomy

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1.3 Speed
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What is Speed and How is it Measured?
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What Do We Mean By Speed?

• The speed of an object is a measure of how
  quickly the object gets from one place to
  another.
• To determine a speed, you need to know two
  things
• the distance traveled.
• the time taken.

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Speed
distance traveled (m)
v d t
speed (m/sec)
time taken (sec)
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Whats the v for?

• Speed the distance covered per unit of time
• Velocity speed and the direction of an object
• Speed 60 km/h
• Velocity 60 km/h due East
• Vector Quantity a quantity that specifies both
  magnitude and direction (example velocity)

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Concepts of Speed and Velocity

• Constant speed steady speed doesnt speed up or
  slow down
• Constant velocity both constant speed and
  constant direction

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How to Solve Scientific Problems

• Step 1
• Identify what you are asked.
• Step 2
• Write down what you are given.
• Step 3
• Write down any relationships you know that
  involve any of the information you are asked, or
  given.
• Step 4
• Pick which relationship to start with and try to
  arrange it to get the variable you want on the
  left-hand side of an equal sign.
• Step 5
• Plug in the numbers and get the answer

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Example

• What is the average speed of a cheetah that
  sprints 100m in 4s? How about if it sprints 50m
  in 2s?
• In both cases the answer is 25 m/s
• Average speed distance covered 100m 50m
  25m/s
• time interval 4s 2s

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