I postet this problem earlier without really getting anywhere so now I'll post the whole thing:
A vertical conveyorbelt has two rollers. A mass hangs in the center of the bottom one to make it taut. On this this belt there are small buckets that scoop up sand in the bottom and then empty this...
a block of mass m is resting on a 20degree slope. The block has coefficients of friction mu_s =0.80 and mu_k =0.50 with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 kg. (sorry didnt know of a way to distribute a picture)...
What is the purpose of a cover slip? Why do we sometimes put one on a slide even though we are not going to keep that slide froever and will inevitably just throw it away? Why (eg - with temporary blood films) do when use oil instead? Why do we sometimes use coverslips instead of oil?
a ladder of mass M and length L leans at an angle theta against a frictionless wall. coefficient of static friction between ladder and ground is MU, what is the minimum angle at which the ladder will not slip? this problem sounds fairly simple, but I've been looking at it for the past 20 minutes...
I read in an old metal working book that when a auto body panel is struck sharply with a hammer that for a microsecond or nanosecond there is a vibration or "shock waves" that allows the grains of metal to slip past one another and re-arrange slight. I am desperately looking for an explanation...