You have an object with a characteristic length of 1.8 cm. For the following conditions, determine the Rayleigh Number (evaluate the fluid properties at the film temperature): a) Water at a free-stream temperature of 50°C; object at a temperature of 14°C. b) Unused Engine Oil, at a temperature of 13°C; object at a temperature of 61°C. c) Air at atmospheric pressure, and a temperature of 11°C; object at a temperature of 43°C.

Please show all your work and formulas used

..P15 A horizontal cylinder 10 cm in diameter contains helium gas at room temperature and atmospheric pressure. A piston keeps the gas inside a region of the cylinder 20 cm long. (a) If you quickly pull the piston outward a distance of 12 cm, what is the approximate temperature of the helium immediately afterward? What approximations did you make? (b) How much work did you do, including sign? (Note that you need to consider the outside air as well as the inside helium in calculating the amount of work you do.) (c) Immediately after the pull, what force must you exert on the piston to hold it in position (with the helium enclosed in a volume that is 20 + 12 = 32 cm long)? (d) You wait while the helium slowly returns to room temperature, maintaining the piston at its current location. After this wait, what force must you exert to hold the piston in position? (e) Next, you very slowly allow the piston to move back into the cylinder, stopping when the region of helium gas is 25 cm long.…

Required information Sometimes equations can be developed and practical problems solved by knowing nothing more than the dimensions of the key parameters. For example, consider the heat loss through a window in a building. Window efficiency is rated in terms of R value, which has the unit of ft2-hr-°F/Btu. A certain manufacturer offers a double-pane window with R = 2.5 and also a triple-pane window with R= 3.4. Both windows are 3.5 ft by 5 ft. On a given winter day, the temperature difference between the inside and outside is 45°F. How much heat is lost through the double-pane window? 315 Btu Return to question