College Physics Chapter 11 Alan Giambattista Betty Richardson Robert Richardson 4th edition Chapter 11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Question 1 Consider a wave on a string moving to the right, as shown. What is the direction of the velocity of a particle at the point labeled A? A) right B) zero C) up D) down

Question 2 Consider a wave on a string moving to the right, as shown. What is the direction of the velocity of a particle at the point labeled B? A) up B) down C) right D) it doesn't move

Question 3 Two waves travel towards each other with v = 10 cm/s. What will be the amplitude of the resultant wave 1 second from now? A) 0.30 cm B) 0.50 cm C) 0.80 cm D) 1.3 cm

Question 4 Two waves travel towards each other with v = 1 m/s. What will be the amplitude of the wave crest when the right-traveling wave reaches x = 4m? A) -7.5 cm B) 12.5 cm C) 5.0 cm D) -2.5 cm

Question 5 A string is clamped at both ends and plucked so it vibrates in a standing mode between two extreme profiles 1 and 2. Let upward motion correspond to positive velocities. When the string is in position 2, the instantaneous velocity of points on the string: A) is zero everywhere B) is (+) everywhere C) is (-) everywhere D) depends on the string

Question 6 A violin string of length L is fixed at both ends. Which one of these is not a wavelength of a standing wave on the string? A) L B) 2L C) L/2 D) L/3 E) 3L/2

Question 7 A violin string of length 0.60 m has a fundamental frequency of 440 Hz. Where should the violinist place her finger so that the string vibrates at 330 Hz? A) 15 cm from the tuning peg B) 30 cm from the tuning peg C) 45 cm from the tuning peg D) This isn't possible.

Question 8 A violinist discovers while tuning her violin that her string is flat (has a lower frequency). She should A) tighten the string. B) loosen the string. C) play faster.

Question 9 Two water striders are on the surface of a pond 1 m apart. You throw a rock in the pond 1 m from the first bug and the ripples cause it to bob up and down with an amplitude of 1 cm. The second bug will have an amplitude of A) 1 cm B) 1/2 cm C) 2 cm D) 1/4 cm

Question 10 A wave moves from point A to point B by A) moving the matter in the medium from A to B. B) moving matter and energy from A to B. C) transferring energy from A to B. D) none of the above.

Question 11 The position of two points on a string differs by one and a half wavelengths. The motion of these two points is A) in phase. B) out of phase. C) uncorrelated.

Question 12 You look inside your piano and find that there are two types of strings: steel wire and steel wire wrapped with a copper coil. If you have one of each type of string with the same length and under the same tension, which will produce a lower frequency sound wave? A) The bare wire will have a lower frequency. B) The wrapped wire will have a lower frequency. C) They will have the same frequency.

Question 13 A traveling wave on a string is described by y(x,t) = A cos(wt + kx). It travels to the left and hits the the point x = 0, where the string is fixed in place. Which function describes the reflected wave? A) A cos(wt + kx) B) A cos(wt - kx) C) -A cos(wt - kx) D) -A sin(wt + kx)

Question 14 The higher the frequency of a wave A) the smaller its speed. B) the shorter its wavelength. C) the greater its amplitude. D) the longer its period.

Question 15 What is the equation of a wave traveling to the right with amplitude 5.0 mm, angular frequency 65 rad/s, and wave number 4 rad/m? A) y(x,t) = (5.0 mm) sin [(65 rad/s)t + (4 rad/m) x] B) y(x,t) = (65 rad/s) sin [(5.0 mm)t + (4 rad/m) x] C) y(x,t) = (5.0 mm) sin [(65 rad/s)t - (4 rad/m) x] D) y(x,t) =(4 rad/m) sin [(65 rad/s)t +(0.0050 m) x]

Question 16 A boat is moored in a fixed location, and waves make it move up and down. If the spacing between wave crests is 20 m and the speed of the waves is 5 m/s, how long does it take the boat to go from the top of a crest to the bottom of a trough? A) 1 second B) 2 seconds C) 4 seconds D) 8 seconds E) 16 seconds

Question 17 You send a wave pulse down a lightweight rope, which is tied to a very heavy rope. At the boundary, A) the reflected wave will be upright and the transmitted wave will be inverted. B) the reflected wave will be inverted and the transmitted wave will be upright. C) the reflected wave will be inverted and the transmitted wave will be inverted. D) the reflected wave will be upright and the transmitted wave will be upright.

Question 18 The tension in a vibrating string is increased by a factor of 4. The fundamental frequency A) increases by a factor of 2. B) increases by a factor of 4. C) decreases by a factor of 4. D) decreases by a factor of 2.

Question 19 A rope of length L and mass M hangs from a ceiling. If the bottom of the rope is pulsed to cause a wave to travel up the rope, the speed of the wave as it travels up A) increases. B) stays the same. C) decreases.

Question 20 If the distance to a point source of sound is tripled, by what factor does the intensity of the sound change? A) Ifar = 9 Inear B) Ifar = 3 Inear C) Ifar = 1/3 Inear D) Ifar = 1/9 Inear

Answer Key – Chapter 11 D A E C B C A D