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 0.47 m and an estimated mass of 0.32 kg. (a) Estimate the total buoyant force on the 600 balloons. (Enter your answer to at least two decimal places.)  kN (b) Estimate the net upward force on all 600 balloons.  kN (c) Ashpole parachuted to Earth after the balloons began to burst at the high altitude and the system lost buoyancy. Why did the balloons burst? Atmospheric pressure at this  high or low altitude is much  lower or higher than at the Earth's surface.

F @ You pull upward on a stuffed suitcase with a force of 135 N, and it accelerates upward at 0.710 m/s². MAR 8 с What is the mass of the suitcase? m= Submit Part B W= 15. ΑΣΦ What is the weight of the suitcase? Request Answer Zal S G Search or type URL [ΫΠ ΑΣΦ MacBook Pro P Pearson tv ? ? N kg

A block, as shown below, is sliding on a thin horizontal layer of water (u = 1.68 x 103 kg/m.s) between ice and the block with a speed of 13 m/s. The thickness of the water layer is 3.32 x 10-5 m. Given the following dimensions of the block, what is the force (F) required to maintain this movement? A = 9 cm B = 9 cm C= 8 cm B 2.96 N 5.33 N 4.14 N 4.74 N

Using whichever model you see suitable, estimate how long gravity will take to flatten a mountain of height H.  Talk about your justifications and assumptions.