15 points to da winner. sophie's credit card has an apr of 19 percent. what is the periodic rate?

1.58 percent
.79 percent
19 percent
2.28 percent

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).