Rubber Band newton Scale

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Rubber Band newton Scale

• Construct a scale with simple
• materials and explore
• Forces
• Newtons 3 Laws
• Mass, Weight, and Gravity
• SI Units of measure

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• Investigation
• Construct a scale
• Explore SI Units of force and motion
• Application of Newtons 2nd Law to
• making calibration weights
• Mass vs. Weight
• F ma and W mg
• Calibrate scale with objects
• Develop a feel for a newton of force
• 6) Test the effect of gravitational force
• on the rubber band.

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• Construct scale
• Use materials listed in handout to build scale.
• Stop when you are ready
• for calibration weights.

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2) Explore SI Units of force and
motion Length (m) meter Mass (kg)
kilogram Time (s) second Force, velocity,
acceleration, and energy are derived from these
units.
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• A force is a push or a
• pull that acts on an object
• Newtons 2nd Law describes how
• net force, the mass of
• the object, and its acceleration
• are related

Force mass x acceleration F ma
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• SI Units and Force
• Force is measured in newtons (N).
• Mass is measured in kilograms (kg)
• Acceleration is the rate at which the velocity
• of an object changes over time, or meters
• per second, per second. (m/s/s) or (m/s2)
• F ma
• F 1 kg x 1 m/s2 1 N
• One newton of force will accelerate a 1 kg
• object at one meter per second, each second.

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• Weight, Mass and Force
• Objects on Earth fall due to the force of
• gravity at an acceleration of 9.8 m/s2
• F ma can be expressed as
• W mg
• Where W is the force of gravity acting on an
• object (or its weight), m is its mass, and
  g is
• acceleration due to gravity
• W 1 kg x 9.8 m/s2 9.8 kg m/s2
• 10 N
• So, if you multiply the mass of an object x ten,
• you have its _at_ weight, in newtons, on Earth.

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Lets practice What is the weight (in newtons)
of .5 kg of water?
W mg W (.5kg) (10m/s2) _at_ 5N
Water has a density of 1g/1mLSo 100 mL of water
has a mass of 100 g .1 kg. Voila! (.1 kg)
(10m/s2) _at_ 1N
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4) Calibrate Rubber Band scale
A small eye-hook and a recycled 500-mL
plastic water bottle can be used as calibration
weights. remember to consider the mass of the
plastic lid, hook, and bottle in
your calculations.
Small, cheap, digital balance to mass objects.
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5) Develop a feel for a newton of force.

• Newtons 3 Laws of motion
• An object will remain at rest or in constant
  motion unless acted upon by a net force.
  (Inertia)
• A net force acting on an object can change its
  acceleration. (F ma)
• When on object exerts a force on a second
  object, the second exerts a force on the first
  object. Forces occur in pairs. (Action and
  Reaction)

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• How does your scale relate to Newtons 3 Laws of
  motion?
• Demonstrate the 3 Laws with your scale.
• Make a labeled drawing of your scale in your
  science notebook.

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• 6) Test the effect of gravitational force on
  the rubber band.
• Measure the distance, in millimeters, between
  the 0 N mark on your scale and each of the
  other calibration marks.
• Create a data table in your notebook.
• Construct a line graph that shows how
• increasing force affects the stretching of the
  rubber band.

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Sample graph results
Hand-drawn
Computer-generated with Verniers Graphical
Analysis software.
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Discussion Predict what a graph would look like
if you used a newton spring scale from the lab,
instead of your own rubber band scale? Sketch the
graph and explain your prediction.
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• Instructional Strategies discussion
• 1) Science Notebooks
• 2) Assessments
• Formative
• Authentic