Why is a universal joint useful?

Ariver flows from north to south at 8 km/h. a boat is to cross this river from west to east at a speed of 20 km/h (speed of the boat with respect to the earth/ground). at what angle (in degrees) must the boat be pointed upstream such that it will proceed directly across the river (hint: find the speed of the boat with respect to water/river)? a 288 b. 21.8 c. 326 d. 30.2

You are making beer. the first step is filling the glass carboy with the liquid wort. the internal diameter of the carboy is 15 in., and you wish to fill it up to a depth of 2 ft. if your wort is drawn from the kettle using a siphon process that flows at 3 gpm, how long will it take to fill?

Which of the following ziegler nichols tuning methods the response of the controller to a step input should exhibit an s-shaped curve? a)-open loop mode b)-closed loop mode c)-both modes (open & closed) d)-none of the modes (open & closed)