During typical urination, a man releases about 400 mL of urinein about 30 seconds through the urethra, which we can model as atube 4.0 mm in diameter and 20 cm long. Assume that urine has thesame density as water, and that viscosity can be ignored for thisflow. What is the flow speed in the urethra? If we assume that thefluid is released at the same height as the bladder and that thefluid is at rest in the bladder (a reasonable approximation), whatbladder pressure would be necessary to produce this flow? (In fact,there are additional factors that require additional pressure; theactual pressure is higher than this.)
