Exam 1 Practice Solution

# Exam 1 Practice Solution - huynh(hph268 Exam 1 Practice...

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huynh (hph268) – Exam 1 Practice – clark – (56485) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points Consider two identical metal bottles A and B that can be used to hold compressed gases. A is flled with air at atmospheric pressure, and B is completely evacuated. Which bottle is denser? 1. A correct 2. B 3. Unable to determine 4. Densities are the same. Explanation: The bottle with air is both heavier and denser. Air has mass, so it will make the air- flled bottle heavier. Since the bottles have the same volume, the one that is heavier is also the one that is denser. 002 10.0 points When an object Falls through air, there is a drag Force ( with dimension M · L / T 2 ) that depends on the product oF the surFace area oF the object and the square oF its velocity; i.e. , F air = C Av 2 , where C is a constant. What is the dimension For constant C ? 1. [ C ] = M T · L 2 2. [ C ] = M T 2 · L 2 3. [ C ] = T M 4. [ C ] = M L 2 5. [ C ] = T 2 · L 2 M 6. [ C ] = M L 3 correct 7. [ C ] = T 2 · L M 8. [ C ] = T · L M 9. [ C ] = T · L 2 M 10. [ C ] = M T Explanation: [ F ] = M · L / T 2 , [ A ] = L 2 , and [ v ] = L / T , so [ C ] = [ F ] [ A ] [ v ] 2 = M · L / T 2 L 2 · (L / T) 2 = M · L T 2 · T 2 L 4 = M L 3 . 003 10.0 points The average person burns up approximately 5 cals/min during exercise while gaining 100 cals From the post exercise snack. Dieticians recommend 30 minutes oF exercise and one snack daily. Using this inFormation, provide an order oF magnitude estimate oF the net caloric change every day in all the health-conscious citizens in a city like Austin (population 7 × 10 5 ). 1. 10 4 kcals 2. 10 kcals 3. 10 4 kcals correct 4. 10 kcals 5. 10 7 kcals 6. Cannot be estimated 7. 10 7 kcals Explanation: In 30 minutes oF exercise you burn 150 calo- ries. Since you gain 100 From the snack, the

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huynh (hph268) – Exam 1 Practice – clark – (56485) 2 net change is 50 calories. The population of Austin is about 7 × 10 5 , so the total caloric change is Δ C ( 50 cal)(7 × 10 5 ) 1 kcal 1000 cal = 35000 kcal . 004 (part 1 of 3) 10.0 points There are roughly 10 59 neutrons and protons in an average star and about 10 11 stars in a typical galaxy. Galaxies tend to form in clus- ters of (on the average) about 10 3 galaxies, and there are about 10 9 clusters in the known part of the Universe. Approximately how many neutrons and protons are there in the known Universe? 1. n 10 52 2. n 10 87 3. n 10 82 correct 4. None of these 5. n 10 47 6. n 10 43 Explanation: Let : N n = 10 59 , N s = 10 11 , N g = 10 3 and N c = 10 9 . The number of particles in the observable
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## This note was uploaded on 09/28/2011 for the course PH 303K taught by Professor Zao during the Spring '11 term at University of Texas.

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Exam 1 Practice Solution - huynh(hph268 Exam 1 Practice...

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