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25 m b 05 m c 1 m d 2 m e 4 m 1m the lowest frequency

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Unformatted text preview: er of the graph each B) 1 C) 2 D) 2.5 This asks for the frequency: f = 3 16. Displacement !y (m) B 2 (a) E) 4 F) 8 v 8 m/s = = 4 Hz. λ 2m D If I pluck a 1 m long string (tied down to two ends), a series of standing waves are set up in the string. The wavelength of the standing wave with the lowest frequency is A) 0.25 m B) 0.5 m C) 1 m D) 2 m E) 4 m 1m The lowest frequency standing wave has a single antinode, and is half a wave. Its wavelength is twice the width of the string: λ = 2 m. Page 8 17. In an incompressible ﬂuid, 3 (a) A the pressure at B is . . . the pressure at point A. A) greater than B) the same as C) less than A 3 (b) 3 18. B the density at B is . . . the density at point A. A) greater than B) the same as C) less than B E A large hole is dug into the ground at a 45◦ angle with the horizontal as shown, and is ﬁlled with water (ρ = 1000 kg/m3 ). What is the pressure at the star, 4 m below the water level? Assume atmospheric pressure is 105 Pa. A) 0.39 × 105 Pa B) 0.45 × 105 Pa C) 0.61 × 105 Pa D) 1.00 × 105 Pa E) 1.39 × 105 Pa F) 1.55 × 105 Pa Patm=105 Pa 4m 45° The pressure 4 m below the surface is P = P0 + ρgh = 105 Pa + (1000 kg/m3 )(9.8 m/s2 )(4 m) = 1 × 105 Pa + 0.39 × 105 Pa = 1.39 × 105 Pa 5cm 1kg 3 19. A cube with mass 1 kg and side 5 cm (and volume 1.25 × 10−4 m3 ) is suspended by a rope in water (ρ = 1000 kg/m3 ). Find the tension in the rope. The forces on the cube are the tension T up, the weight mg = 9.8 N down, and the buoyancy force Fb = ρVd g = (1000 kg/m3 )(1.25 × 10−4 m3 )(9.8 m/s2 ) = 1.23 N upwards. Thus T + 1.23 N = 9.8 N =⇒ T = 8.6 N Page 9 20. The ﬁgure shows a wooden cube (0.5 m on each side) ﬂoating in water (ρ = 1000 kg/m3 ). The top of the cube is 0.2 m above the level of the water. 3 (a) 0.5m 0.2m 0.3m D Find the density of the wood. A) 200 kg/m3 B) 400 kg/m3 C) 500 kg/m3 D) 600 kg/m3 E) 800 kg/m3 Let ρ be the density of the wood, and A = (0.5 m)2 be the area of the top of the cube. It feels two forces:...
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This note was uploaded on 01/15/2014 for the course PHYSICS 2130 taught by Professor Scotthill during the Spring '12 term at Toledo.

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