4a. When a 4.39kg mass is hung vertically on a certain light spring that obeys Hooke's law, the spring stretches 2.62cm. If the 4.39kg mass is removed how far will the spring stretch if a 1.60kg is hung on it instead? 9.5mm Submit Answer Submission not graded. Use more significant figures. Tries 0/10 Previous Tries 4b. How much work must an external agent do to stretch the spring 3.97cm from its unstretched position? 2.60J Submit Answer Incorrect. Tries 1/10 Previous Tries