1. The problem statement, all variables and given/known data David used a sling to kill Goliath. The mass of the rock was 2.5 kg and the sling had a length of 1.2 m. If it spun horizontally 2 m above his head 7 times in 3 seconds: a. What was the launch velocity? b. What is the centripetal force and tension? c. How far is David from Goliath? 2. Relevant equations Fc=mv^2/r F=ma Fc=m4(pi^2)r/t^2 3. The attempt at a solution I tried setting ma=mv^2/r, but that would only give me the velocity it spins at, not the velocity at which it was launched. And I'm not sure what to do with the 2 m. Assistance would be great, I've been trying this for 2 hours and still nothing.