Coefficient of Friction Lab
Planning B –
Apparatus:
- Pulley (minimum friction)
- String (minimum friction)
- Sandpaper sheet
- Wooden block
- Various masses (5g, 10g, 20g.. etc)
- Mass-hook (holder)
- Sticky tape
- Electronic scale (one per class)
Method:
- Gather all necessary materials listed above
- Using the electronic scale, measure the mass of the wooden block and record this, taking into account uncertainties where applicable.
- Attach the string to the wooden block, and the other end to a mass-hook.
- Place the sheet of sandpaper underneath the block and tape the sheet firmly in place on the table using sticky-tape (also note the exact position of the block on the sheet as we will try to keep that constant throughout)
- Screw on the adjustable pulley at one edge of a laboratory table
- Hang the mass hook off the table, using the mass pulley – if this already causes the block to move, then place a small weight on top of the block. You set-up should look the following:
- Carefully, while having your partner keeping an eye on the stationary block, add small increments of weight onto the hanging mass hook.
- Once you have gone too far and the block has moved, remove the last weight and place the block back into its starting position. You will now have to add smaller increments of weight to determine more precisely how much force was needed.
- When you are satisfied with the amount of weight, remove it and measure everything that is on the hook (including the mass hook itself) using the electronic scale. Do not rely on the mass readings on the masses themselves, as time and wear has significantly decreased the mass shown.
