What is the volume of a sphere with a radius of 21 units? O A. 9261 7 units
O B. 12,348 units3
O C. 5887 units
D. 37,04477 units3

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).