In order for the standard of living within a country to be enhanced over time, which of the following is essential?

a. The role of the country’s government in the economy must become larger.
b. The population of the country must increase.
c. More domestic natural resources must be discovered and used.
d. The level of productivity must increase.

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).