General Equipment
Force Table part
- force table
- slot masses and hangers
- 4 table pulleys
- center post for table
- ring with four strings attached
- list of force table "problems"
"Traffic Light" Problem
- Force probe
- table clamp
- tabel pole
- right-angle clamps, short poles
- single pulley
- box masses
Force probe reading "negative"? Here are directions to help you collect and graph the "inverted" force readings (so outward is positive and inward is negative).
Center post and ring with string
You can check to make sure the forces are balanced by noting if the ring is centered around the post .. not touching. Also in this picture, you can see the slot masses - a variety of sizes should be available (some thick masses, some thin masses).
Hanging masses = "Forces"
To create the "forces" for the force table situations, use the string over the pulleys connected to the mass hanger. Different slotted masses can be used to create the forces required (remember, the hanger itself has a mass of 50 grams!).
"Traffic Light" model
This is the general picture for the traffic light problem. The force probe points "upward", and the string goes over a pulley, down to the other "free" pulley (that can roll along the string), and back up to an anchor point on the far left.
Make sure that the system is aligned so that all the strings are in one plane ... thus the string is not "twisted" around the top pulley, and that the force probe is reading the correct force value.
"Anchor" end of the pulley string
It doesn't really matter how you anchor the pulley string - just wrapping it, or tying it around a free right-angle clamp would be fine.
Hanging mass from pulley
You should hang the mass from the bottom hook of the free pulley - the pulley allows the mass to "slide" freely along the string (it "rolls" to the bottom of the string).
The use of this rolling pulley ensures that the angles on either side are the same.
