To investigate what factors effect the force of friction you can make a block with four different types of materials on a block of wood with a hook at attach a spring score or force probe.
For this project you will need:
wooden fence post
square of carpet
square of flannel
square of faux alligator
dish of water
Step 1: Cutting the Blocks
Step 2: Adding the Materials
I choose to use gorilla glue so that the materials would be firmly adhered. I tried using wood glue about three years ago and the materials slowly peeled off the blocks, I'm hoping that this glue choice will last longer.
Gorilla glue requires that you dampen the surfaces, spread a thin layer of the glue, and weight down or clamp the bond line while its setting. This step is not required with other glues. Make sure you read the specific directions on whatever you choose for your project.
Step 3: Add a Hook
When you drag the block along a surface with a force probe you can pick the static friction force and kinetic friction force off of a graph of force vs. time. Then by weighing the block you can also look at the coefficient of friction for starting motion and continuing motion.
It helps to have at least one per lab group for their investigations.
Step 4: Uses in the Classroom
- How does the combination of different surfaces effect the magnitude of the force of friction?
- How does adding weight to a block impact the force of friction? (The students can add weights onto the top of the block.)
- How does adding weight to a block impact the coefficient of friction?
and many other investigations as well!