Can sound be produced in a vacuum? explain?

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

A0.750 kg aluminum pan is removed from the stove and plunged into a sink filled with 10.0 kg of water at 293 k. the water temperature quickly rises to 297 k. what was the initial temperature of the aluminum pan? the specific heat of aluminum is ca = 900 j/(kgk) and water is cw = 4190 j/(kgk)

Relative to the ground below, how many joules of potential energy does a 1000-kg boulder have at the top of a 5-m ledge?