question: A skydiver will reach what when the air drag equals their weight?
distractor3: ending velocity
distractor1: constant velocity
distractor2: building velocity
correct_answer: terminal velocity
support: viscosity. Using the equation of the previous problem, find the viscosity of motor oil in which a steel ball of radius 0.8 mm falls with a terminal speed of 4.32 cm/s. The densities of the ball and the oil are 7.86 and 0.88 g/mL, respectively. A skydiver will reach a terminal velocity when the air drag equals their weight. For a skydiver with high speed and a large body, turbulence is a factor. The drag force then is approximately proportional to the square of the velocity. Taking the drag force to be F D = 1 ρAv 2 and setting this 2 equal to the person’s weight, find the terminal speed for a person falling “spread eagle. ” Find both a formula and a number for v t , with assumptions as to size. A layer of oil 1.50 mm thick is placed between two microscope slides. Researchers find that a force of 5.50×10 −4 N is required to glide one over the other at a speed of 1.00 cm/s when their contact area is 6.00 cm 2 . What is the oil’s viscosity? What type of oil might it be? 42. (a) Verify that a 19.0% decrease in laminar flow through a tube is caused by a 5.00% decrease in radius, assuming that all other factors remain constant, as stated in the text. (b) What increase in flow is obtained from a 5.00% increase in radius, again assuming all other factors remain constant? 43. Example 12.8 dealt with the flow of saline solution in an IV system. (a) Verify that a pressure of 1.62×10 4 N/m 2 is created at a depth of 1.61 m in a saline solution, assuming its density to be that of sea water. (b) Calculate the new flow rate if the height of the saline solution is decreased to 1.50 m. (c) At what height would the direction of flow be reversed? (This reversal can be a problem when patients stand up. ) 44. When physicians diagnose arterial blockages, they quote the reduction in flow rate. If the flow rate in an artery has been reduced to 10.0% of its normal value by a blood clot and the.