A grindstone in the shape of a solid disk with diameter d and a mass of M is rotating at angular velocity . You press an ax against the rim with a normal force and the grindstone comes to rest in time t. Find the coefficient of friction between the ax and the grindstone. You can ignore friction in the bearings.

The amount of heat required to change liquid water to vapor at its boiling temperature is 2256 kj/kg. the amount of heat required to change liquid mercury to its vapor state at its boiling temperature is 295 kj/kg. one kg of each substance is currently at its boiling point. how will the amount of thermal energy required to change each substance from a liquid to a gas differ?