Acrew team rows a boat at a rate of 20 km/h in still water. in practice on a river, the team rows for 30 minutes up the river (against the current), and then for 30 minutes down the river (with the current). the speed of the river current is 1.5 km/h. how much farther did they travel in the second 30 minutes?

Asquare isothermal chip is of width w=5 mm on a side and is mounted in a substrate such that its side and back surfaces are well insulated; the front surface is exposed to the flow of a coolant at tinf=15 °c. from reliability considerations, the chip temperature must not exceed t=85 °c. if the coolant is air and the corresponding convection coefficient is h=200 w/m2 x k, what is the maximum allowable "power" of the chip? if the coolant is a liquid for which h=3000 w/m2 x k, what is the maximum allowable power of the chip?