What is the molecular mass of magnesium chloride, mgcl2?

(how do you get to the answer as well)

Why does the input force have to be greater than the force needed to lift the bale?

Which bonds are found inside a water molecule

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.