# Physics

**Chapter 6 Fluids and Motion**

1. About how fast can a small fish swim before experiencing turbulent flow around its body?

2. How much higher must your blood pressure get to compensate for 5% narrowing in your blood vessels? (The pressure difference across your blood vessels is essentially equal to your blood pressure.)

3. If someone replaced the water in your home plumbing with olive oil, how much longer would it take you to fill a bathtub?

4. You are trying to paddle a canoe silently across a still lake and know that turbulence makes noise. How quickly can the canoe and the paddle travel through water without causing turbulence?

5. The pipes leading to the showers in your locker room are old and inadequate. Although the city water pressure is 700,000 Pa, the pressure in the locker room when one shower is on is only 600,000 Pa. Use volume=(π* pressure different* pipe diameter^4)/ (128* pipe length*fluid viscosity)] to calculate the approximate pressure if three showers are on.

6. If the plumbing in your dorm carried honey instead of water filling a cup to brush your teeth could take awhile. If the faucet takes 5 s to fill a cup with water, how long will it take to fill your cup with honey, assuming all the pressures and pipes remain uncharged?

7. How quickly would you have to move a 1-cm-diameter stick through olive to reach a Reynolds number of 2000, so that you would begin to see turbulence around the stick? (Olive oil has a density of 918 kg/m^3)

8. The effective obstacle length of a blimp is its width- the distance to which the air is separated as it flows around the blimp. How slowly would a 15-m-wild blimp have to move to keep the airflow around it laminar? (Air has a density of 1.25kg/m^3)

**Chapter 7 Heat and Phase Transitions**

9. You stir 1 kg of water until its temperature rises by 1. How much work did you do on the water?

10. While polishing a 1-kg brass statue, you do 760 J of work against sliding friction. Assuming that all the resulting heat flows into the statue, how much does its temperature rise?

11. You drop a lead ball on a cement floor from a height of 10 m. When the ball stops bouncing. How much will its temperature have risen?

12. Roughly how high could a 300 K copper ball life itself if it could transform all its thermal energy into work?

13. Drilling a hole in a piece of wood takes 1000 J of work. How much does the total internal energy of the wood and drill increase as a result of this process?

14. An ideally efficient freezer cools food to 260 K. If room temperature is 300 K, how much work does this freezer consume when removing 100 J of heat from the food?

15. An ideally efficient refrigerator removes 900 J of heat from food at 270 K. How much heat it then deliver to the 300 K room air?

16. An ideally efficient heat pump delivers 1000 J of heat to room air at 300 K. If it extracted heat from 260 K outdoor air, how much of that delivered heat was originally work consumed in the transfer?

17. An ideally efficient air conditioner keeps the room air at 300 K when the outdoor air is at 310 K. How much work does it consume when delivering 1240 J of heat outside?

18. An ideally efficient airplane engine provides work as heat flows from 1500 K burned gases to 300 K air. What fraction of the heat leaving the burned gases is converted into work?

19. An ideally efficient steamboat engine operates on 500 K steam in 300 K weather. How much work can it obtain when 1000 J of heat leaves the steam?

20. An offshore breeze at the beach is powered by heat flowing from how land (310 K) to cool water (290 K). Assuming ideal efficiency, how much work can this breeze provide for each 1000 J of heat it carries away from the land?

21. An ideally efficient solar energy system produces work as heat flows from the 6100 K surface of the sun to the 300 K room air. What fraction of the solar heat can it transform into work?

**Chapter 8 Thermodynamics**

22. What is the wavelength of a tuba’s A^2(110-Hz) tone in air at standard conditions?

23. A piccolo is playing A^6(1760 Hz). What is the wavelength of that tone in air at standard conditions?

24. When a piano plays C^(260 Hz) in a room containing a somewhat unusual mixture of gases, the wavelength of the sound in that gas is 1,00m. What is the speed of sound in that gas?

25. At an altitude of 3000m and standard temperature (0), a violins A^4(440 Hz) has wavelength of 0.725m. What is the local speed of sound?

26. A water surface wave with a frequency of 0.3 Hz has a wavelength of 17.3m. What is its wave speed?

27. A water surface wave has a wave speed o 15.6m/s and a frequency of 0.1 Hz. What is its wavelength?