A cylindrically shaped piece of collagen is being stretched by a force that increases from 0 to 3.0 x 10^-2 N. The length and radius of the collagen are 2.5 and 0.091 cm. Young's Modulus is 3.1 x 10^6 N/m^2. a.) If the stretching obeys Hooke's Law, what is the spring constant, k, for the collagen? b.) How much work is done by the variable force that stretches the collagen?