1. The problem statement, all variables and given/known data A slingshot consists of a light leather cup, containing a stone, that is pulled back against two parallel rubber bands. It takes a force of 15 N to stretch either one of these bands 1.0 cm. (a) What is the potential energy stored in the two bands together when a 50-g stone is placed in the cup and pulled back 0.20 m from the equilibrium position? (b) With what speed does the stone leave the slingshot? The answers are a) PE = 60 J b) v = 49 m/s 2. Relevant equations F=kx PE=1/2kx^2 3. The attempt at a solution a) F=kx 15 = k(0.01) → k=1500 N/m PE = 1/2 k x^2 = 1/2 (1500)(.20)2 = 30 J b) PE1=KE1, KE = 1/2mv^2 1/2mv^2 = 30 1/2(0.050)v^2 = 30; v= 34.6 m/s Any comment or help would be appreciated about why I got the answers wrong. Thank you.