According to Hooke's Law, the force required to hold the spring stretched xm beyond its natural length is given by f(x) = kx, where k is the spring constant. Suppose that 3 J of work is needed to stretch a spring from its natural length of 34 cm to a length of 49 cm. Find the exact value of k, in N/m. k = N/m (a) How much work (in J) is needed to stretch the spring from 42 cm to 44 cm ? (Round your answer to two decimal places.) (b) How far beyond its natural length (in cm) will a force of 25 N keep the spring stretched? (Round your answer one decimal place.) cm
