How long does a knot have to be tied to be considered a "קשר של קימא". (Knot of permanence).
is one allowed to push a pill through silver foil;
ודבר דבר (Dabair Davar): Talking About Calculations on Shabbos;
What Do We Mean by Leaning on a Tree? Items on a Tree Going into Shabbos Remain Muktzeh;