No internet resources can be used to complete the assignment. Use graph paper to graph the data.
Consider a spring and a rubber band. Both have elastic properties, which means that as their
lengths increase, they exert increasing amounts of force. Let “stretch length” represent the
difference between the spring or rubber band’s length while it exerts force and its length while it
exerts no force.
Carlos suggests that both the spring and rubber band exert a force that is directly proportional to
their stretch length.
Experimental Design Describe a procedure that Carlos could perform to make measurements
that would allow him to show evidence for his claim. Assume that Carlos has access to a spring,
a rubber band, and equipment typically found in a school physics laboratory. Describe the
measurements to be made and with what equipment. Include enough detail that another student
could follow the procedure.
1. Collect a spring, a rubber band, ruler, and spring scale
2. Put the spring on to the spring scale.
3. Now pull the spring until the scale reaches 10 N
4. As you are holding the force applied, measure the stretch length of the spring
5. Continue to repeat the process until 50 N are applied
6. It is the same process with the rubber band.
No internet resources can be used to complete the assignment. Use graph paper to graph the data.
Does the graph show evidence that supports Carlos’s claim? Be sure to address both the spring’s
behavior and the rubber band’s behavior. Why or why not?
The graphs on the excel spreadsheet supports Carlos’s claim because his claim was that that both
the spring and rubber band exert a force that is directly proportional to their stretch length. This meant
that his graph need to have a line or near to close to a line based off his data. The line of best fit showed
that both were basically linear. Both graphs went under the linear regression test to find the R^2 value (a
statistical measure that represents the proportion of the variance for a dependent variable that's explained
by an independent variable or variables in a regression model). The R^2 runs from 0-1 and both graphs
showed R^2 as 0.99, which indicates that the model explains all the variability of the response data
around its mean.
Dominique reads that race cars have wide tires because the increased area of contact between the
tire and the road results in a stronger force of friction. She hypothesizes that the force of kinetic
friction on an object is directly proportional to the area of the object in contact with the surface
and wants to test this hypothesis.
Dominique and Blake take a long wooden plank and cut the plank into pieces that have different
lengths but the same width and height. The students also have access to other equipment
commonly available in a school physics laboratory.
Experimental Design Explain how Dominique and Blake could determine the force of kinetic
friction exerted on one of the wooden piece.
The students collect the following data.
1. Collect a wooden plant, ruler, spring scale, logger pro or PASCO Capstone, TI-84, and
scale
2. Measure the area of each block and the volume of each block
3. Use of the coefficient of friction of wood
4. To find the normal force take the mass of each block and multiply by the gravitational
acceleration.
5. To the Kinetic Friction Force, multiply the normal force by the coefficient of friction.
6. To find out if they are proportional to each other plot the values of area and the Kinetic
Friction Force on the stat button on the TI-84. As area in L1 and the Friction in L2
7. Turn on the stat plot on and take the linear regression test
8. Do the same with volume
No internet resources can be used to complete the assignment. Use graph paper to graph the data.
On the grid, plot a graph of the data that could be used to test Dominique’s SPECIFIC
hypothesis. Label both axes with quantities, units, and an appropriate scale. Draw a best-fit line
to the data.
Does the graph itself support Dominique’s hypothesis? Why or why not?
The graph with area vs Friction does show proportionality with an R^2 value of .9963 and an
equation of y = 39.2x + 0.006. However, that doesn’t mean that Dominique’s hypothesis is true
because in the volume vs Friction graph, it also shows proportionality. The equation for the
volume graph is y = 1960x + .006 with an R^2 value of .9963. They both have the same yintercept and R^2 value. So the question is: what affects friction? Although a larger area of
contact between two surfaces would create a larger source of frictional forces, it also reduces the
pressure between the two surfaces for a given force holding them together. Since pressure equals
force divided by the area of contact, it works out that the increase in friction generating area is
exactly offset by the reduction in pressure; the resulting frictional forces, then, are dependent
only on the frictional coefficient of the materials and the force holding them together. force of
friction directly depends on the volume of the block. Force of friction depends on the mass of
No internet resources can be used to complete the assignment. Use graph paper to graph the data.
block. Mass of the block is product of density of block and volume of the block. So, force of
friction directly depends on the volume of the block. So, Dominique’s hypothesis is incorrect
because of those reasons stated above.