[net.physics] physics in a moving car

rokhsar@lasspvax.UUCP (Dan Rokhsar) (08/31/84)

     The string holding the fuzzy dice has to provide the inward 
pointing force to keep the dice moving in a circle, otherwise they
would travel in a straight line and leave the car quickly.  The 
string must also provide enough force to keep the dice from falling, 
that is it must give an upward force counteracting gravity.

The dice are suspended away from the 
center of the curve so that the string     _____________________________
can provide the inward force                           /|
     force inward = string tension x sine of angle    / | with vertical
     force upward = string tension x cosine of angle /  |
so the string tension = upward force /cosine        /   |
                      = g x mass / cosine          []
the centripetal force needed = mass x velocity **2 / radius
so the angle that the string makes with vertical can be solved for.

                          Dan Rokhsar