Approximately how fast can the wind blow past (a) a 0.25-in.-diameter twig if viscous effects are to be of importance throughout the entire flow field (i. e., Re < 1)

List 3 options on how to reduce knocking problens during engine process,

Asimple speed reducer is composed of 2 spur gears. the pinion gear has a pitch diameter of 0.75" and 36 teeth while the driven gear has a pitch diameter of 4.0" and 192 teeth. a)-what is the diametral pitch of each gear? b)-if an electric motor rotating ccw at 3000 rpm is coupled to the pinion, what is the rotational speed of the driven gear? c)-if the torque delivered to the pinion is 1 n-m, what is the torque on the driven gear? d)-what is the power transmitted by the gear train?

The crank case of an automobile is 80 cm long 30 cm wide and 10 cm deep. find out the rate of heat flow from the crank case to the atmosphere when the automobile is moving at 90 km/hr. assume that the vibration of the engine and the chassis iaduce the transition from laminar to turbulent boundary layer may be considered over the entire surface. also find out the drag force on the total surface of the crank case. take the same average convective heat transfer coefficient and average shear stress for front and rare surfaces as for the bottom rnd sides crank case surface temperature is 75°c and atmospheric air temperature is 5 c