Introduction to Forces

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Lesson 5

• Introduction to Forces

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Background

• Force push or pull on or by an object
• Newton (N) metric unit of force

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Types of Force

• Elastic Force associated with materials that
  stretch easily
• Gravitational Force attraction between to
  bodies based on mass and distance

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The Spring Scale

• Answer questions A-D on page 37 after examining
  the spring scale.

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Question

• How does force change when you stretch a rubber
  band?

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Hypothesis

• The further a rubber band stretches the more
  elastic force it has.

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Materials

• Pegboard assembly, rubber band, spring scale
  (10N), meter stick

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Procedure

• See page 38-39 of lab manual

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Task

• Follow procedures found on page 38-39
• Complete data table and questions found on your
  table. (in your notebook)
• Draw a line graph from your data. (remember where
  the independent and dependent variables go).
• Answer questions from your graph found on your
  table. (in your notebook)

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Analysis

• Student data sheet and graph.

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Conclusion

• As the stretched distance of a rubber band is
  increased the elastic force also increased. Each
  time the distanced was doubled, the measured
  force was nearly doubled. Our data and graph
  show this increasing trend to be consistent.

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New Questions

• How does the elastic force of a rubber band
  change the more its used?

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Lesson 5.2

• Gravitational Force

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Family Guy

• Brian explains gravity to Peter

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Background

• Remember the difference between mass and weight
• Mass is the amount of matter in an object.
  Weight is the force exerted on a mass.

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• Mass is measured in grams (g), kilograms (kg)
• Weight is measured in newtons (N)

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Question

• What determines the weight of an object?

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Hypothesis

• As an objects mass increases, so does its weight.

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Materials

• Spring scale, balance, washers

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Procedure

• See group poster.
• (Design a procedure to test your hypothesis and
  write down your steps on poster paper to share
  with the class)

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Analysis

• See student data sheet and graph.
• (Design a table like the one you used with the
  rubber band. Display your results on a graph)

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Conclusion

• As the number of washers increased so did their
  combined masses. Each of the washers were also
  weighed on the spring scale. The results gave
  evidence that as the mass increased so did the
  weight. Our data and graph also prove this change
  to be consistent.

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New Question

• If the force of gravity changes, how is an
  objects weight affected?

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Reading

• Hooke and Newton Geniuses at Work

Read pages 45-47.Answer the questions in your
notebook.
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Bungee Jumping!!!
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