1405 Bending Lab Name __________________
Materials:
2-meter stick and Ruler
Knife-edge Blocks (air-cars will also work)
Gram Mass Set
Equation
Stiffness = Force causing deformation / size of deformation
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 5 different lengths.
Bending Lab Report
Instructions:
Neatly Print (or type) your report in your own words in the format below.
Part 1 Elasticity
1) What is meant when we say a material is elastic? Is your stick elastic? Explain in
complete sentences.
Part 2 Deformation vs. Load
1) Make and attach a neat, well-labeled, Data Table for Part 2 with correct units.
2) 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.
3) The stiffness of your stick is related to the slope of a line connecting nearby data points.
Does the stiffness of your stick depend significantly on the load? Explain by carefully
examining the slope of your graph.
4) Calculate the stiffness of your stick in newtons/cm from the data for a 500gram load.
Show your equations, units, and work.
Part 3 Stiffness vs. Blocked-Length
1) Make and attach a neat, well-labeled, Data Table for Part 3 with correct units.
2) Choose two blocked lengths for which one is double the length of the other. By what
factor is the stiffness changed when the blocked length was doubled? Show your data,
units, and work.
3) Characterize the Stiffness as equal to, less than, or greater than: proportional, inverseproportional, inverse-square proportional to the Blocked-Length.