You are using hard chromium electroplating on a sphere. Air at a temperature of 18°C (P = 1 atm) and a velocity of 18.2 m/sec flows over the sphere that was just removed from the electroplating process. The sphere has a diameter of 0.05 m, and is at a temperature of 62°C. a) Calculate the heat transfer rate (q). b) Calculate the drag force on the sphere.

b Estimate the radius of the cylindrically shaped crater that such a comet strikes the Moon. Assume that the crater, of depth 10 km, is formed by heating to 3,500 K, and thus vaporizing, a cylindrical volume of moon rocks. Moon rocks are made of silicates, which have molecular weights of ~ 30 (i.e., m cm°. Ignore the latent heat required to melt and vapourize the rocks, and the energy involved in vapourizing the comet itself. creates when it 30 mH), and mean solid densities p ~ 2 g/ ~

Question 9 Consider the flow of water over a flat plate. In a different experiment consider the flow of air over a flat plate. In both cases the flow is steady, the boundary layers that are formed are laminar and the gravitational acceleration can be neglected. In both cases the velocity far from the plates is the same (v.) and the temperature is also the same (80 °F). For the same distance x from the leading edge, in which boundary layer will the friction coefficient be higher? (a) The friction coefficient is the same for both cases. (b) In water. (c) In air. (d) It depends on the velocity profile that is assumed inside the boundary layer.

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A thin, flat plate of length L = 1 m seperates two airstreams that are in parallel flow over opposite surfaces of the plate. One airstream has a temperature of T,1=200°C and a velocity of uo,1= 60 m/s, while the other airstream has a temperature of T,2= = 25°C and a velocity 10 m/s. What is the heat flux between the two streams at the mid point of the of u0,2 plate?