1. A 20kg boy holds a number of helium balloons each with volume 5000cm3 and mass 3g. How many balloons can the boy hold before he starts to be lifted off his feet?2. Slack lining is doing tricks while standing on a rope stretched between two trees as shown in the photo. A 60kg person standing in the middle of a 5m rope causes it to go down 50cm. Calculate the tension in the rope.