2(l + w) is used to calculate the perimeter of a rectangle, where l is length and w is width. if the length is fraction 2 over 7 unit and the width is fraction 3 over 7 unit, what is the perimeter of the rectangle in units?

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).