An empty rubber balloon has a mass of 0.0220 kg. The balloon is filled with helium at 0°C, 1 atm pressure, and a density of 0.179 kg/m^3. The filled balloon has a radius of 0.700 m. a. What is the magnitude of the buoyant force acting on the balloon? ( density of air= 1.29)
b. What is the magnitude of the net force acting on the balloon

Consider a small frictionless puck perched at the top of a fixed sphere of radius r. if the puck is given a tiny nudge so that it begins to slide down, through what vertical height will it descend before it leaves the surface of the sphere? [hint: use conservation of energy to find the puck's speed as a func e conservation of energy to find the puck's speed as a function of its height at what value of this normal force does the puck leave the sphere? ] here on the puck.