Where did the word electricity come from

Two steel balls, each of mass m, are welded to a light rod of length l and negligible mass and are initially at rest on a smooth horizontal surface. a horizontal force of magnitude f is suddenly applied to the rod as shown. determine (a) the instantaneous acceleration a of the mass center g and (b) the corresponding rate at which the angular velocity of the assembly about g is changing with time.

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is as it changes into other forms of energy.

The three classes of rocks are sedimentary, metamorphic, and igneous. how are rocks classified into one of these three groups?