Chapter 14: Answers to Stop to Think Questions and Odd-Numbered Exercises and Problems

Stop to Think Questions

  1. 1. ρA=ρB=ρC. Density depends only on what the object is made of, not how big the pieces are.

  2. 2. c. These are all open tubes, so the liquid rises to the same height in all three despite their different shapes.

  3. 3. a. The pressure from the weight of the column of mercury balances the air pressure pushing on the surface of mercury in the beaker. The air pressure is zero after the air is pumped out, so a mercury column of any height would not be in balance.

  4. 4. b. The weight of the displaced water equals the weight of the ice cube. When the ice cube melts and turns into water, that amount of water will exactly fill the volume that the ice cube is now displacing.

  5. 5. 1 cm3/s out. The fluid is incompressible, so the sum of what flows in must match the sum of what flows out. 13 cm3/s is known to be flowing in, while 12 cm3/s flows out. An additional 1 cm3/s must flow out to achieve balance.

  6. 6. h2>h4>h3>h1. The liquid level is higher where the pressure is lower. The pressure is lower where the flow speed is higher. The flow speed is highest in the narrowest tube, zero in the open air.

Exercises and Problems

  1. 1. 50 mL

  2. 3. 1.4×105 kg

  3. 5. 1.013×105 Pa

  4. 7.

    1. 6.3 m3

    2. 1.2×105 Pa

  5. 9. 3 km

  6. 11.

    1. 106 kPa

    2. 4.4 kPa, 4.4 kPa

  7. 13. 3.2 m

  8. 15. Ethyl alcohol

  9. 17. 750 kg/m3

  10. 19. 1.9 N

  11. 21. 2.49×103 kg/m3

  12. 23. 55.6 kg

  13. 25.

    1. 1.0 m/s, 16 m/s

    2. 3.1×10−4 m3/s

  14. 27. 2.12 m/s

  15. 29.

    1. 0.38 N

    2. 20 m/s

  16. 31. 3.1×102 Pa

  17. 33. 0.53 atm

  18. 35. 5.5×109 N/m2

  19. 37.

    1. 5.1×107 Pa

    2. −0.025

    3. 1056 kg/m3

  20. 39. 2.4 μm

  21. 41. 87 mm Hg

  22. 42. 26 psi

  23. 43.

    1. 0.48 m

    2. 58 kg

  24. 45. 3.7 mm

  25. 47.

    1. F=ρgDWL

    2. F=12ρgD2L

    3. 0.78 kN, 1.4 kN

  26. 49. 8.01%

  27. 51. 8.9×102 kg/m3

  28. 53. 18 cm

  29. 55. 5.2 cm

  30. 57.

    1. p1=p0+12ρv02 (1−d04d14)

    2. 75 kPa

  31. 59.

    1. p2=patmos

    2. 4.6 m

  32. 61.

    1. Lower

    2. 0.83 kPa

    3. Blow out

  33. 63.

    1. v1=1.4×102 m/s, v2=5.8 m/s

    2. 4.5×10−3 m3/s

  34. 65.

    1. vhole Ahole=πr22gd1−(r/R)4

    2. 1.1 mm/min

  35. 67. 480 kPa

  36. 69. 0.043 L/min

  37. 71. 76 cm

  38. 73.

    1. p0=patmos

    2. d=12p0h+16ρgh2p0+12ρgh

  39. 75. 53 kPa