Learning Goal: The Reynolds Number RN quantifies the nature of fluid motion relative to the surface of a solid body. The Reynolds number is a dimensionless ratio and is given by RN = LP where v is the velocity of the fluid relative to the solid surface, L is the length of the flow path over the surface, p is the density of the fluid, and n is the viscosity of the fluid. The Reynolds number is basically the ratio of the magnitude of inertial forces moving the fluid divided by the magnitude of viscous forces. When the Reynolds number is small i.e. RN << 1 viscous forces dominate and the fluid moves slowly over the solid body in a laminar fashion, A large Reynolds number RN >> 1 indicates that fluid is accelerating rapidly over the fluid surface under the influence of inetial forces. When RN 2 2000 the fluid flow becomes turbulent. Large objects (i.e. large L) moving rapidly (i.e. large v) through a low voscosity fluid (i.e. low n) have large Reynolds numbers. Small objects moving slowly through viscous fluids have low Reynolds numbers. Here we explore how motions through fluids with high and low Reynolds numbers differ. Part A Large objects like fish move through water by using their fins to accelerate water around them. Such motion is dominated by inertial forces. Suppose a fish that is L = 10.0cm in length moves at v = 0.250cm · s-1 through water at T=298K, Assume at T=298K water has a density of p = 1.00g · mL-1 and a viscosity of 7 = 0.001PA · s. Calculate the Reynolds number for the fluid adjacent to the surface of the fish. RN = 250 Submit Previous Answers v Correct Part B Small objects like one cell organisms do not use fins to propel themselves through water. They do not have propulsion systems that accelerate water around them but rather use flagella which exploit frictional interactions with the fluid. Suppose a one cell organism with a length of L = 1.00 × 10-4cm moves through water at a velocity of v = 2.50 × 10-3cm · s-1.. Assume T=298K. Calculate the Reynolds number for the fluid around this one-celled organism. RN = 2.50x10-5 Submit Previous Answers v Correct

Learning Goal: The Reynolds Number RN quantifies the nature of fluid motion relative to the surface of a solid body. The Reynolds number is a dimensionless ratio and is given by RN = LP where v is the velocity of the fluid relative to the solid surface, L is the length of the flow path over the surface, p is the density of the fluid, and n is the viscosity of the fluid. The Reynolds number is basically the ratio of the magnitude of inertial forces moving the fluid divided by the magnitude of viscous forces. When the Reynolds number is small i.e. RN << 1 viscous forces dominate and the fluid moves slowly over the solid body in a laminar fashion, A large Reynolds number RN >> 1 indicates that fluid is accelerating rapidly over the fluid surface under the influence of inetial forces. When RN 2 2000 the fluid flow becomes turbulent. Large objects (i.e. large L) moving rapidly (i.e. large v) through a low voscosity fluid (i.e. low n) have large Reynolds numbers. Small objects moving slowly through viscous fluids have low Reynolds numbers. Here we explore how motions through fluids with high and low Reynolds numbers differ. Part A Large objects like fish move through water by using their fins to accelerate water around them. Such motion is dominated by inertial forces. Suppose a fish that is L = 10.0cm in length moves at v = 0.250cm · s-1 through water at T=298K, Assume at T=298K water has a density of p = 1.00g · mL-1 and a viscosity of 7 = 0.001PA · s. Calculate the Reynolds number for the fluid adjacent to the surface of the fish. RN = 250 Submit Previous Answers v Correct Part B Small objects like one cell organisms do not use fins to propel themselves through water. They do not have propulsion systems that accelerate water around them but rather use flagella which exploit frictional interactions with the fluid. Suppose a one cell organism with a length of L = 1.00 × 10-4cm moves through water at a velocity of v = 2.50 × 10-3cm · s-1.. Assume T=298K. Calculate the Reynolds number for the fluid around this one-celled organism. RN = 2.50x10-5 Submit Previous Answers v Correct