Investigation #4Stretching the LimitsStretching the Limits

Investigating Elastic Energy & EarthquakesInvestigating Elastic Energy & Earthquakes

What makes some materials better able to store EPE?

How do materials store EPE?

Are all materials elastic?

Energy is all around us. Sometimes it is stored in elastic materials as Elastic Potential Energy (EPE)

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 MaterialsInvestigating Elastic Materials

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!

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

Investigation Reflection1. 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 & DistanceHow are the EPE and the distance

that an elastic material is stretched or compressed related?

Investigating Elastic Force & Elastic Potential EnergyInvestigating 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 Reflection1. 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 EarthquakesInvestigating 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.