1405 13 2008c
Bending Lab
Materials:
2-meter stick and Ruler
Knife-edge Blocks (air-cars will also work)
Gram Mass Set
Objectives:
Explore elasticity and force-deformation behavior of a stick.
Determine “stiffness” of stick.
Determine dependence of stiffness on size of object.
Instructions: – Record all data in your notebook.
Part 1 Elasticity
1.
2.
3.
4.
5.
Block the 2m stick at 10cm and 190cm.
Carefully measure the height of the center of the stick.
Add 500 grams to the center of the stick.
After about 30 seconds, remove the mass, and re-measure the height.
Repeat this process two more times.
Part 2 Deformation vs. Load
1. Block the 2m stick at 10cm and 190cm.
2. Note the length of stick between the blocks. For example, if blocked as
above, the length blocked is 190 – 10 = 180cm.
3. Measure the height of the center of your 2m stick from the top of your lab
table (the extra space on ruler, if any, will not matter)
4. Add 50grams to the center of the 2m stick. Measure the new height of the
center.
5. Continue adding 50grams, noting the new center height, until you have
reached 600grams total.
Part 3 Stiffness vs. Length
1. Move each block 10cm closer to the center of the 2m stick. For example, if
blocked at 10cm and 190cm, move the blocks to 20cm and 180cm.
2. Measure the height at the center.
3. Add 500grams to the center, and re-measure the height.
4. Unload the stick.
5. Move each block 10cm closer to the center.
6. Re-measure the height at the center.
7. Add 500grams to the center, and re-measure the height.
8. Repeat this process until you have data for 6 different lengths.
1405 13 2008c
Bending Lab Report
Instructions:
Neat Print or Typed
Data Tables must be in order within the report and with correct labels &
units.
Graphs may be attached at end of report.
Part 1 Elasticity
A. Report all Part 1 data here in a labeled data table.
B. What is meant when we say a material is elastic? Is your stick elastic?
Explain in complete sentences.
Part 2 Deformation vs. Load
A. Data.
Report all Part 2 data here in a labeled data table.
Make, and attach, a graph where the y-axis is the distance the center
moves in cm when a load is added and the x-axis is the added load in
grams. Label each axis correctly and title the graph by Length blocked.
B. The stiffness of your stick is related to the slope of a line connecting
nearby data points. Does the stiffness of your stick depend on the load?
Explain by carefully examining your graph.
C. Calculate the stiffness of your stick in grams/cm for a 500gram load by
dividing the deflection in cm into 500grams. Show all work below.
Part 3 Stiffness vs. Length
A. Data.
Report all data taken in a data table. Add a column titled “stiffness”, which
contains the ratio 500grams/cm-deflection.
Make, and attach, a graph where the y-axis is stiffness in grams/cm and
the x-axis is the blocked-length in cm. Label each axis correctly and title
the graph “Stiffness vs. Length”.
B. Describe the relationship of stiffness to length by carefully examining your
graph. Characterize your graph as proportional, inverse-proportional,
inverse-square proportional as was done in class. Explain in complete
sentences.