On October 21, 2001, Ian Ashpole of the United Kingdom achieved a record altitude of 3.35 km (11,000 ft) powered by 600 toy balloons filled with helium. Each filled balloon had a radius of about 0.53 m and an estimated mass of 0.28 kg.
(a) Estimate the total buoyant force on the 600 balloons.
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(b) Estimate the net upward force on all 600 balloons.
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