In the motion picture Danny Deckchair, based on an real event, a man attaches 42 helium-filled weather balloons to an aluminum deck chair, steps in, and takes off to experience a series of adventures. (Don't try this at home - or anywhere else!) The weight of the man plus the chair plus the balloons is 934 N. Each balloon is a sphere 1.60 m in diameter. The density of air at sea level and 15°C is 1.23 kg/m3. Find the net upward force on Danny and his vehicle right after he leaves the ground? Neglect the volume of the man and of the deckchair.