a hot-air balloon is accelerating upward under the influence of several forces. the hot air inside the balloon has a density of 0.930 kg/m3, and the density of the cool air outside is 1.29 kg/m3. the mass of the balloon fabric and basket is negligible. find the acceleration of the rising balloon. include in your solution a free-body diagram for the balloon.

The ratio of lift to drag l/d for a wing or airfoil is an important aerodynamic parameter, indeed, it is a direct measure of the aerodynamic efficiency of the wing. if a wing is pitched through a range of angle of attack, l/d first increases, then goes through a maximum, and then decreases. consider an infinite wing with an naca 2412 airfoil. estimate the maximum value of l/d. assume that the reynolds number is 9x10^6.

Which accurately compares concave and convex lenses?

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.1 m below the tank bottom which is a = 7.4 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute)