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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.
 Spring '12
 ScottHill
 Physics, Acceleration

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