All of the letters in the word “P-R-O-B-A-B-I-L-I-T-Y” are in a bag.
What is the theoretical probability of choosing a vowel? P(vowel)

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).