What effect does air resistance have on the projectile

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?

The substances that are necessary for producing of certain hormones and that store and transport vitamins

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.