Investigation 4

							 Investigation #4
            Stretching the Limits
Investigating Elastic Energy & Earthquakes
    Energy is all around us. Sometimes it is stored in elastic
         materials as Elastic Potential Energy (EPE)




 What makes
some materials
 better able to
  store EPE?

How do materials
  store EPE?

Are all materials
    elastic?
            Journal Entries:
• Journal Entry #1: List some examples of elastic
  materials and describe how you think these materials
  would store elastic potential energy.


• Journal Entry #2: Do elastic materials always return to
  their original shape and/or position? If not, what might
  cause them not to do so?
Elastic Forces & EPE
  What are elastic properties and how
  do they help predict how an elastic
        material will behave?
         Investigating Elastic Materials

     Focus Question: How are elastic forces and their stretch
                     related?



Use the force probe to
explore the relationship
between the elastic force
and the stretch distance for
several elastic materials.

Be sure to click on the
KEEP icon each time you
collect a data point!
     Investigation Reflection
1.   When scientists interpret their data after an investigation, they look
     for patterns that emerge. What patterns emerge from your data?

2.   The slope of the line in a linear graph tells the reader about the
     relationship between the dependent variable (the force) and the
     independent variable (the stretch distance).
     Click on the Linear Regression button in the tool bar. What is the
     slope (m= value) of each line?

3.   Are the slope values the same for all trials? If they are different,
     what may have caused any differences you observe? Are these
     differences significant? Explain.

4.   Predict the force needed to extend each spring 2 cm farther than
     your last data point. On what do you base this prediction?
5.   Predict the force needed to extend each spring 20 cm
     farther than your last data point. On what do you base this
     prediction?

6.   Which of the above predictions do you think is more likely to
     be accurate? Explain.

7.   What are the limitations of this procedure that may affect
     the accuracy of your data?
          Equation Review
• What is the kinetic energy of 3750kg car
  moving at 50 m/s?
• What is the GPE (or PE) for a car with a
  mass of 1400 at the top of a hill that is 8 m
  high.
• How much work needs to be done to move
  a 155 N car up a 14.2 m hill?
• If Justin’s mass is 100 kg and he runs up a
  set of stairs that are 2m high in 20
  seconds, how much power does he have?
EPE & Distance
  How are the EPE and the distance
that an elastic material is stretched or
         compressed related?
Investigating Elastic Force & Elastic Potential Energy

Focus Question: How is EPE related to the stretch or compression
                distance of the elastic material?




  Your task is to explore how the EPE is related to the amount
  compression of a spring inside the car.
  Is it a simple relationship or a complex one?
     Investigation Reflection
1.   The plunger spring is compressed approximately 2cm for each setting, so
     setting #1 compresses the spring 2cm while setting #3 compresses the
     spring 6cm. How does the average distance traveled by the car up the ramp
     compare at each setting? Does it represent a simple or a complex
     relationship?


2.   Describe the relationship between the compression of the spring and the KE
     attained by the car just after the car pushes off of the end stop. Design a
     graphical illustration, possibly an energy diagram or an energy chain, of this
     relationship.


3.   The distance the car moves along the track in not equal to the GPE it attains.
     Why is this so? How could the GPE of the car be determined?
EPE & Earthquakes
 How does EPE relate to the
   study of earthquakes?
    Investigating Earthquakes

Focus Question: How are elastic forces and their stretch
                related?




Your task is to explore how earthquakes occur because of a
transformation of EPE to KE by using a model.