Suppose you buy a 122 cm wide and 244 cm long sheet of plywood and put it on your roof rack, as shown in You drive home at 56 km / h. The temperature of air is 20ºC, and the sheet of plywood can be assumed to be a sharp edged flat plate. The influence of car on the flow of air past the sheet of plywood can be neglected. (a) Assuming the board is perfectly aligned with the air flow, how thick is the boundary layer δ at the end of the board? [8] (b) Estimate the drag on the sheet of plywood if the boundary layer remains laminar. [6] (c) Estimate the drag on the sheet of plywood if the boundary layer is turbulent (assume the wood is smooth). [6]

 

Figure Q2.