254, [T] A mass hanging from a vertical spring is in simple harmonic motion as given by the following position function, where is measured in seconds and is in inches: - o s(t) = 3cos (vt + ). a. Determine the position of the spring at t = 1.5 s. b. Find the velocity of the spring att = 1.5 s. 256. [T] The formula for the area of a circle is A = ':rr'i"?, where 1 is the radius of the circle. Suppose a circle is expanding, meaning that both the area A and the radius 7 (in inches) are expanding. 100 dd _ dA dr 7 7y where is time in seconds. Use the chain rule I & to find the rate at which the area is expanding. b. Use a. to find the rate at which the area is expanding att = 4 s. a. Suppose T 2