Connecting a series of cells together creates what?

Which of the following is considered to be a vector?               a.  temperature    b.  velocity    c.  time    d.  mass

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.

If the area of a square has increased by a factor of 16, by how much has each side increased?