Estimate the 99% boundary layer thickness in the following cases (1) A light breeze over a flat building roof (length=15 m, velocity=5 m/s) (2) A wind passing over an ocean (length=2km, velocity=150 km/h) The kinematic viscosity of air is 1.5x10^(-5) m^2/s. Calculate the Reynolds number based on the boundary layer thickness (instead of the length scale shown above) and the velocity scale in these flows. We assume these flows to be laminar. Choose two answers for the results.

A simple thermometer is formed by taking a large spherical container of volume 1.13m³ and filling it with an ideal gas. Then, a U-shaped tube is attached that is very narrow so that very little fluid/gas can fit inside the tube. The tube has a small quantity of a fluid of density 1200kg/m³ placed in it. In equilibrium at room temperature - 21.9°C - the height of the fluid on both sides of the U-shaped tube are level. This is illustrated in the image below. What is the temperature of the gas in the spherical container when the left side of the fluid is 13.25cm higher than the right side of the fluid in the U-shaped tube? Atmospheric pressure is 101000Pa. °C

Bacteria have a density that is about the same as water. Their average velocity is 10^-3 m/s. A bacterium with a radius of 1 um should have a diffusion coefficient of about 2.2x10^-13 m^2/s. (a) Find the random-walk step size (b) How long does it take for an average walk to reach 1 mm in seconds and days? Note that we are considering the diffusion away from the starting point and are calculating the distance through three dimensions. Show your work

A smooth circular hole in the bottom of a metal cylinder is 0.04mm in diameter. Ethanol is filled into the cylinder until it drips from the hole. Since the surface tension of the ethanol wetting the metal at ambient temperature is 22.3 dyn / cm and its density is 0.789 g / cm3, what is the minimum height of the ethanol in the cylinder for dripping to begin?