General Setup

Basic equipment needed :

• 1 force probe
• 1 motion sensor
• 1 protection cage for the motion sensor (not shown)
• 2 USBLink
• 1 track with a pulley and a stopper at one end (pulley and stopper shown later on page)
• 1 string to hang over pulley
• 1 box masses and 1 mass hanger
• 1 plexiglass L-bracket (not shown)

Force probe mounted on Cart?

There are two holes on the force probe, find the one labeled as "Cart", plug the black screw (you may have a silver one) through it and fasten the probe onto a cart. There are groovs on the bottom of the sensor, they must match the ridges of the cart.

Pulley end of the track

Please adjust the pulley up and down so that the string from the force probe on the cart runs exactly parallel to the track (horizontal). Notice the "stopper" is also placed onto the track - that will keep the cart from knocking the pulley off the track (try to stop the cart just before it hits the metal stop if possible.

String should be horizontal!

As indicated above ... make sure that the string coming out from the force probe is horizontal as it leads to the pulley (and also, it should be in the CENTER of the track .. that is, the pulley should not be to one side or the other.

Why do we care about the horizontal string?? Well, if the string is not horizontal, then the force from the force probe is not being read correctly ... AND, it gets worse .. as the cart gets closer to the pulley, the "angle" of the string would change .. leading to a non-constant force!