Physics 1303,1403 - Spring 1997

Homework Assignment #8

Due:
1 May (Sections 002 and 802)
2 May (Sections 001 and 801)

READING

Chapter 15.

QUESTIONS

Chapter 15 - 2, 3, 7, 8, 9, 10, 25, 27, 29, 31.

PROBLEMS

Chapter 15 - 3, 7, 5, 12, 18, 24, 25, 31, 37, 39, 42, 49, 68, 70.

Bonus:
Visit one of the Web sites at the bottom of the Physics 1303 Web Page and write a 300 word description/critique of it.

ANSWERS

These are the ANSWERS only, not the SOLUTIONS. It is not sufficient to copy these and turn them in as homework. You must show your work.

Q 15-2) 1000 newtons (about 220 lbs)

Q 15-3) A straw will not work on the Moon.
Q 15-7) Higher in ocean because salt water is more dense than fresh.
Q 15-8) 4080 m2
1,000,000 newtons = weight of water displaced = (2.5 cm)x(Cross-sectional area of ship)x(g)x(density of water).
Q 15-9) The same, since they displace the same volume of water.
Q 15-10) The level stays the same.
Q 15-25) The balloon does not rise to the ceiling.
Q 15-27) The amount of the block submerged decreases. The water level in the tub remains the same.
Q 15-29) Regular soda contains sugar dissolved in water, which is more dense than pure water, or water with aspertame.
Q 15-31)
  1. The air is moving with highest speed in the narrow section of the pipe (middle); this is where the pressure is least.
  2. The pressure at the left is slightly lower than the pressure at the right, but not as low as the pressure in the middle. Even though the tube has the same dimensions, some air pressure is lost through the middle hole as the air stream travels from right to left.
P 15-3) 5 x 1017 kg/m3 No chemical elements come anywhere near this density; atoms are mostly empty space.
P 15-7) 4.8 x 1017 kg/m3 (same as nuclear density)
P 15-5) 6.24 x 106 Pa
P 15-12) bottom: 5.87 x 106 N
end: 196,000 N
side: 588,000 N
P 15-18)
  1. 20 cm
  2. 0.49 cm
P 15-24) 621
P 15-25) 1470 N
P 15-31) 0.611 kg
P 15-37)
  1. 17.7 m/s
  2. 1.73 mm
P 15-39) 12.8 kg/s
P 15-42) 27 m/s
P 15-49) 2 sqrt[h (ho-h)]
P 15-68)
  1. Proof required
  2. 26,000 N (5800 lbs)
P 15-70) 196 kg/s

Please report any corrections to Professor Scalise.

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