Why doesn’t earth get larger when new rock is added to the ocean floor at the mid-ocean ridge? !

Ahydroelectric plant takes energy from water and turns it into electrical energy. what are the transformations of energy in the water molecules that are used in the process of generating electricity this way?

Find v(t), given acceleration a(t)=7j and initial velocity v(0)=k

Which best represents the law of conservation of mass ?