Suppose that 5 J of work is needed to stretch a spring from its natural length of 28 cm to a length of 43 cm. (a) How much work (in J) is needed to stretch the spring from 36 cm to 38 cm? (Round your answer to two decimal places.) Incorrect: Your answer is incorrect. J (b) How far beyond its natural length (in cm) will a force of 50 N keep the spring stretched? (Round your answer one decimal place.) Incorrect: Your answer is incorrect. cm