Physics+1200+Lab-9

Physics 1200 - Lab#9 Page 1 of 8 Name ______________________________ Partner(s): ___________________________________________________________ Lab 9: Fluids Objectives Study Pressure, Buoyancy force, Fluids in motion Equipment Computer with LoggerPro, force probe, a solid metal cylinder (or a solid metal bar), a hollow metal bar, tall cylindrical beaker, beaker, lab jack, and water. Note: Identify all the pieces of equipment at your table before beginning your lab activities. Ask your lab instructor if you have any questions .

Physics 1200 - Lab#9 Page 2 of 8 Activity 1 Buoyancy You will investigate how the buoyant force exerted by water on a mass depends on the volume of the mass submerged. Draw a free-body diagram for an object of mass, m, hanging from a string while submerged in water. Identify all the forces acting on the object and write the equation of Newton’s second law. You will submerge a solid brass cylinder or a solid copper bar (whichever is available at your table) in a graduated tall cylinder filled with water as shown in the picture. 1) Have the water level between 400 ml – 450 ml in the tall cylindrical beaker. Extra water is available in the short beaker. 2) Zero the force probe (click on the zero-button next to Collect on logger-pro screen) before hanging the cylinder (or bar) to the force probe. Force probe reading is the tension force in the string. 3) Attach the cylinder (or bar) to the force probe with the help of a string. The weight reading in the air (before immersing in the water) corresponds to zero cm depth immersed in the water. Record it in Table-1. 4) Slowly raise the beaker using the jack support so that the object is immersed in water by 1.0 cm. Make sure the hanging metal is not touching the beaker. Record the weight corresponding to 1.0 cm depth in the Table-1 . Continue this process in one cm increments until the top of the object is 2.0 cm below the surface of the water. É t my

Physics 1200 - Lab#9 Page 4 of 8 5) How does the buoyant force vary with the depth in your experiment? 6) Explain your experimental observation. 7) If you immersed a solid metal cone of height, 8.0 cm, instead of the object you used in the above experiment, will you get the same buoyant force variation with the depth immersed? If not, draw qualitatively , the expected buoyant force variation with the depth immersed. (Assume the base of the cone enters the water first.) Show the graph you have drawn to your lab instructor before going to the next activity. depth and FBouyant share a positive correlation There is man weight therefore the Buoyant force will increase via Archimedes principle

Physics 1200 - Lab#9 Page 5 of 8 Activity 2 Lab Challenge: Archimedes’ Principle and the Determination of Mass Density ρ . Your lab challenge today is to find the mass density of an unknown material (hollow metal bar on your lab table). Mass density is the ratio of the mass of an object to its volume and it is a characteristic property of the material of that object. If the mass and volume are known the density can be easily obtained. Volumes of regularly shaped objects like a cube, sphere, cylinder, etc. can be calculated using geometric principles. However, determining the volume of an irregularly shaped object is difficult. As a result it is often easier to determine the mass density of an object by the use of Archimedes’ principle, which states: the buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by that object . 1) Your group is given a piece of material and asked to determine its mass density. By definition mass density = mass/volume. a) Measure the weight of the object in air using the force probe and determine the mass of the object. W(in air) = _____________ m object = ______________ b) Measure the weight of the object in water by carefully immersing it in a beaker of water. Has the weight of the object increased or decreased in comparison with its weight in the air? Give your reason for the observed weight difference in air and water. W(in water) = _____________ 0.43N 0.044kg 0.26N

Physics 1200 - Lab#9 Page 7 of 8 Activity 3 Group Work: Find the speed of air in a Venturi tube Shown below is a Venturi tube with a water-filled manometer attached to Pipes 1 and 2. Air is flowing from left to right in the horizontal tubes. For your calculations purpose assume air is incompressible fluid. Inner diameter of Pipe 1 = 2.63cm; Inner diameter of Pipe 2 = 1.55cm. ρ (air) = 1.20 kg/m 3 ; ρ (water) = 1000 kg/m 3 . Ask your lab instructor for the height difference in the manometer (u-tube filled with water) = ___________ cm. 1) Which side of the manometer (u-tube filled with water) has greater pressure? Explain your answer. 2) Determine the pressure difference P 1 – P 2 . 30 Left side has more presses because there force is zgoing down jeanoea A D 1000 9.850630

Physics 1200 - Lab#9 Page 8 of 8 3) How is the speed of the air flowing through Pipe 1 related to the speed of the air in Pipe 2? Hint: consider the equation of continuity. 4) What is the relationship between the speeds of the air in Pipes 1 and 2 and their pressure difference? Hint: Consider Bernoulli’s equation. 5) Calculate the speed of air, v 1 , in Pipe 1. Result of calculation: v 1 = (check with your lab instructor) 6) Experimentally, what would you do to cause the height difference h in the manometer to increase? Explain. 7) If the air flows in the opposite direction (right to left) what happens to the water in the manometer columns? Explain. End of Lab 9 speed ofpipe two would be faster because it has less area than pipe 0 speed and pressure share a negative correlation p IPvitDgy P ttzpvitpgyzzauoto.eu 4 a v g y o.oizisitvi o.oossst.tv 0.007752 2990 4.3 up 602.25 0 25.9 v 25.9 I would increase the diameter of the left side to lower the speed It would be the same Speed and diameter are the same