# Tutorial 8 States of Matter Solids Fluids by 1GQKdP35

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```									                          Tutorial 8 : States of Matter – Solids & Fluids

12–4 Elasticity; Stress and Strain (Chapter 12)

34. (I) A nylon string on a tennis racket is under a tension of 275 N. If its diameter is 1.00
mm, by how much is it lengthened from its untensioned length of 30.0 cm?
35. (I) A marble column of cross-sectional area 1.4 m 2 supports a mass of 25,000 kg. (a)
What is the stress within the column? (b) What is the strain?
37. (I) A sign (mass 1700 kg) hangs from the end of a vertical steel girder with a cross-
sectional area of 0.012 m 2 . (a) What is the stress within the girder? (b) What is the
strain on the girder? (c) If the girder is 9.50 m long, how much is it lengthened? (Ignore
the mass of the girder itself.)
39. (II) A 15-cm-long tendon was found to stretch 3.7 mm by a force of 13.4 N. The tendon
was approximately round with an average diameter of 8.5 mm. Calculate Young’s
modulus of this tendon.

13–2 Density (Chapter 13)

2. (I) What is the approximate mass of air in a living room 5.6 m 3 3.8 m 3 2.8 m?
Ans: 77 kg
3. (I) If you tried to smuggle gold bricks by filling your backpack, whose dimensions are
56 cm 3 28 cm 3 22 cm, what would its mass be?
13-3 Pressure in Fluids

15. (II) (a) Determine the total force and the absolute pressure on the bottom of a
swimming pool 28.0 m by 8.5 m whose uniform depth is 1.8 m. (b) What will be the
pressure against the side of the pool near the bottom?
17. (II) Water and then oil (which don’t mix) are poured into a U -shaped tube, open at both
ends. They come to equilibrium as shown in Fig. 13–49. What is the density of the oil?
[Hint: Pressures at points a and b are equal. Why?]

13–7 Buoyancy and Archimedes’ Principle

26. (I) What fraction of a piece of iron will be submerged when it floats in mercury?
Ans: 57%

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29. (II) A spherical balloon has a radius of 7.35 m and is filled with helium. How large a
cargo can it lift, assuming that the skin and structure of the balloon have a mass of 930
kg? Neglect the buoyant force on the cargo volume itself.
34. (II) A scuba diver and her gear displace a volume of 65.0 L and have a total mass of
68.0 kg. (a) What is the buoyant force on the diver in seawater? (b) Will the diver sink
or float? Ans: (a) 653 N

13–8 to 13–10 Fluid Flow, Bernoulli’s Equation

50. (II) A 6.0-cm-diameter horizontal pipe gradually narrows to 4.5 cm. When water flows
through this pipe at a certain rate, the gauge pressure in these two sections is 32.0 kPa
and 24.0 kPa, respectively. What is the volume rate of flow? Ans: 7.7 × 103 m3/s
52. (II) What is the lift (in newtons) due to Bernoulli’s principle on a wing of area 88 m 2 if
the air passes over the top and bottom surfaces at speeds of 280 m/s and 150 m/s,
respectively?     Ans: 3.2 × 106 N
54. (II) Water at a gauge pressure of 3.8 atm at street level flows into an office building at a
speed of 0.68 m/s through a pipe 5.0 cm in diameter. The pipe tapers down to 2.8 cm in
diameter by the top floor, 18 m above (Fig. 13–54), where the faucet has been left open.
Calculate the flow velocity and the gauge pressure in the pipe on the top floor. Assume
no branch pipes and ignore viscosity. Ans: 2.2 m/s ; 2.0 atm

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