Physics HW 15

# Physics HW 15 - homework 15 MOHAJER CHRISTOPHER Due May 6...

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homework 15 – MOHAJER, CHRISTOPHER – Due: May 6 2008, 4:00 am 1 Question 1, chap 18, sect 2. part 1 of 1 10 points A cowboy at a dude ranch fills a horse trough that is 1 . 6 m long, 64 cm wide, and 47 cm deep. He uses a 2 . 1 cm diameter hose from which water emerges at 1 . 1 m / s . How long does it take him to fill the trough? Answer in units of min. Question 2, chap 18, sect 2. part 1 of 2 10 points Calculate the mass flow rate of blood (of density 1 g / cm 3 ) in an aorta with a cross- sectional area of 2 cm 2 if the flow speed is 40 cm / s. Answer in units of g / s. Question 3, chap 18, sect 2. part 2 of 2 10 points Assume that the aorta branches to form a large number of capillaries with a combined cross-sectional area of 2900 cm 2 . What is the flow speed in the capillaries? Answer in units of mm / s. Question 4, chap 18, sect 2. part 1 of 1 10 points A 4 meter long hose of 2 cm diameter is connected to a faucet, and a 3 meter long hose, which has a diameter of 4 cm diameter, is connected to the end of the first hose. At the open end of the second hose water flows out at a rate of 2.5 liters/minute. The open end of the second hose is 2 meters higher than the faucet. What is the ratio of the speed of the water in the second hose to the speed of the water flowing in the first hose? 1. 4 2. 1/4 3. 1/2 4. 2 5. 8 6. 1/8 7. 3/2 8. 1 Question 5, chap 18, sect 3. part 1 of 2 10 points You blow up an ordinary party balloon with air until it has a diameter of 8 inches. Your friend blows up another balloon with helium gas until it has a diameter of 12 . 5 inches. Air consists mostly of O 2 and N 2 molecules, while helium gas consists of He atoms. Assume the pressure in each balloon is the same. Compare the number of helium atoms to the total number of O 2 and N 2 molecules. Question 6, chap 18, sect 3. part 2 of 2 10 points Air is about 80% nitrogen and 20% oxy- gen. Compare the weights of the two bal- loons. ( Hint: Imagine that there are 80 he- lium atoms in the helium balloon. Calculate the mass, in atomic mass units, of this amount of helium, and then compare to the mass of the corresponding number of oxygen and ni- trogen molecules.) Question 7, chap 18, sect 3. part 1 of 2 10 points A medic applies a force of 95 N to a 0 . 03 m 2 area that is bleeding. What is the pressure in pascals that she applies? Answer in units of Pa. Question 8, chap 18, sect 3. part 2 of 2 10 points What is the pressure in pounds per square inch? Answer in units of lb / in 2 .

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homework 15 – MOHAJER, CHRISTOPHER – Due: May 6 2008, 4:00 am 2 Question 9, chap 18, sect 3. part 1 of 2 10 points In a 99 s interval, 898 hailstones strike a glass window of area 1 . 101 m 2 at an angle 29 to the window surface. Each hailstone has a mass 2 g and a speed 8 . 3 m / s. If the collisions are elastic, find the average force on the window. Answer in units of N.
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• Spring '09
• KLEINMAN
• Physics, Work, Pressure measurement, CHRISTOPHER –

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