Purpose:

This last week we've been talking about forces. In this lab we will explore how these ideas can give us a small amount of insight into the behavior of rubber bands. This lab will involve making plots which you will then need to embed in your lab report by whatever means you find most successful.

• I) Process Description: To begin this experiment you will need a number of rubberband of the same size, a way to suspend the rubber band from one end, and some lab weights and hangers to allow you to apply known forces to the rubber bands. Your initial task is to sketch your set up with a weight hanging from the rubber band. Do a force sketch of the forces acting on the lab weight. This will allow you to determine the force that the rubber band puts on the weight. How is this related to the force the weight puts on the rubber band?

• II) Stretch: You are aware that the more force you apply to the rubber band the longer it will get. In this case we want to consider a slightly different feature of the rubber band, we want ot know how much it stretches. Be sure you think about how length and stretch are different. What we want to know is how much the rubber band stretches for different forces. What range of forces (weights) should you use? Why will you make those choices? Make a data table of the stretch of the rubber band for the different forces you applied.

• III) Plot: Now you will plot your data points on a standard linear graph. For consistency lets plot the force as a function of the stretch (though the stretch as a function of force makes sense as well). Make sure you have your data converted to appropriate units for force and stretch. Is 0,0 an actual data point for your experiment? .

• IV) Equation of the line: Can you draw a line on your plot that closely approximates the behavior of your data? What is the equation of that line in slope intercept form? In physics we call the slope of that line the "spring constant". What is the spring constant for your rubbber band? Did other folks in the lab get similar numbers?

• V) Multiple Rubber Bands: Explore what happens when you have multiple rubber bands side by side (in parallel) or linked end to end (in series). Which of these has a bigger spring constant? What observation or measurement supports your statement?

LAB DELIVERABLES (turn in):

An introduction and 5 (or more) paragraphs describing your data and calculations for each of the steps above. In each section present any actual measurements, explanations and descriptions of the task you are working on, calculations that you make, and comments on the results.