Question
1. In a Oklahoma College physics lab experiment, a piece of balsa wood is completely submerged under the water. The wood is at rest and is tethered by a string to the bottom of a container of water. The balsa wood has volume is 1.34x10 -6m3 and density of 0.16 x10 3 kg/m3. Water, on the other hand, has density 1.00x103 kg/m3. Answer the following questions and show all work and reasoning.
(a) What is the direction of the buoyant force acting on the wood, up or down ? Circle
In a Oklahoma College physics lab experiment, a piece of balsa wood is completely submerged under the water. The wood is at rest and is tethered by a string to the bottom of a container of water. The balsa wood has volume is 1.34x10 -6 m3 and density of 0.16 x 103 kg/m3. Water, on the other hand, has density 1.00 x 103 kg/m3. Answer the following questions and show all work and reasoning. (a) What is the direction of the buoyant force acting on the wood, up or down ? Circle "up" or "down." (b) What is the direction of the tension force acting on the wood, up or down ? Circle "up" or "down." ? (c) What is the direction of the force of gravity acting on the wood, up or down ? Circle "up" or "down." ? (d) What is the magnitude T of the tension in the string? You are a medical professional attempting to explore the problem of blood pressure drops in diseased, narrowed arteries. The arteries have approximately circular cross-section. In a section of an artery, the diameter d1 is 0.0050 m and the speed v1 of the blood is 0.500 m/s. The section narrows into another segment of artery with diameter d2 = 0.0022 m. The height relative to the laboratory floor does not change (y1 = y2). The density of blood is 1.06 x 103 kg/m3. (a) What is the circular cross-sectional area A1 of the first section of artery? (b) What is the circular cross-sectional area A2 of the second section ? (c) What is the speed v2 in the narrow section of artery? (d) What is the pressure difference P1 - P2 between the two sections? (e) Short answer in sentence form or math form; just clearly explain your work: It was mentioned in class a drop in pressure could lead to the collapse of the narrow section of artery. Explain. What would be one major consequence of such a collapse?
Explanation / Answer
1. a. Up
b. Down
c. Down
d. 0.16 * 1.34 x 10^-6 * 9.8 + T = 1 * 1.34 x 10^-6 * 9.8
T = 11.031 x 10^-6 N
2. a. A1 = pi*d1^2/4 = 1.96 x 10^-5 m^2
b. A2 = pi*d2^2/4 = 3.801 x 10^-6 m^2
c. v1A1 = v2A2
v1 = 0.5 m/s
v2 = 2.58 m/s
d. P1 - P2 = Density(v2^2 - v1^2)/2 = 3.39 x 10^3 Pa
e. Heart Attack
