Inertia and friction: The tablecloth trick

1. Nov 6, 2004

no_brainer

A birthday cake is resting on a a tablecloth at the center of a round table of radius r=12. IThe tablecloth is the same size as the tabletop. You grab the edge of the tablecloth and pull sharply. The tablecloth and the cak are in contact for time t after you start pulling. The sliding cake is then stopped by the friction between the cake and tabletop. The coefficient of kinetic friction between the cake and the tablecloth is Uk=0.3 and between the cake and tabletop is U=0.4. Assume that the cake moves a distance of d while still on the tablecloth and therefore a distance of (r-d) whle sliding on the tabletop. Assum that the friction forces are independend of the relative speed of the sliding surfaces.

A. Calculate maxt value for t if the cake is not to end up on the floor.
B. Does result depend on mass of cake and tablecloth?
Does magnitude of force apply on the tablecloth affect the results?

HElP!!!..I'm stuck..I try doing everything with this problem..Can someone tell me what I need to do. I tried using work, forces..and nothing works...What am I doing wrong...ANy suggestions?