Suppose that 5 J of work is needed tn stretch a spring from its natural length at 26 cm to a length of 33 cm. (a) How much work (In J) is needed to stretch the spring from 31 cm to 36 cm" (Round your answer to two decimal places) J (b) Haw far beyond lts natural length (In cm) will a force at 20 N keep the spring stretched? (Round your answer one decimal place.) Cm