What’s the meaning of pi and how to find the volume of a cylinder. Only do number 1 !!

Yo need asap pls ! markin da brainiest too !

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).

Find the volume v of the solid obtained by rotating the region bounded by the given curves about the specified line. y = x â’ 1 , y = 0, x = 5; about the x-axis v = sketch the region. sketch the solid, and a typical disk or washer.