The surface of a 50-mm-diameter, thin-walled tube is maintained at 100 c. in one case air is in cross flow over the tube with a temperature of 25 c and a velocity of 30 m/s. in another case air is in fully developed flow through the tube with a temperature of 25 c and a mean velocity of 30 m/s. compare the heat flux from the tube to the air for the two cases.

Cathy is pedaling down a steep hill on her bicycle and wants to be able to coast up the next hill, which is 25 meters high, without pedaling. cathy and her bicycle have a mass of 75 kg. assuming her bicycle is 100% efficient, what would her speed have to be?

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?

Lightning is an example of what phenomenon? a release of a large amount of energy an absorption of a large amount of energy a natural electric circuit a natural electric current