This is my gr. 11 physics problem that I can't get. I would be very grateful if someone could help me. A hot air balloon has a force of gravity of 3000N but has an upward force of 3800N due to the hot air. Person A is on the ground and pulling the balloon with a force of 540N [Left 40degree Down]. Person B is pulling with a force of 700N straight down. Person B's rope is 30m long. How long will it take to pull the balloon down. The problem is #52 from p148 of Irving Physics and the answer is 7.5 seconds but I have no idea how they got it there. Thanks for any help you might give!