12) When is the angular momentum of a system constant? A) Only when the moment of inertia is constant. By Only when its total kinetic energy is constant. c) Only when the linear momentum and the energy are constant. D) Only when no net external torque acts on the system. E) Only when no net external force acts on the system. 13) What is the wavelength of the wave shown in the figure? y (m) - 1(8) A B m. B) 1 m. () 4 m. D) 2 m. E) It cannot be determined from the given information. 14 In many canoon shows, a character runs off a cliff, realizes his predicament, and lets out a scream. He continues to scream as he falls. If the physical situation is portrayed correctly, from the vantage point of an observer at the foot of the cliff, the pitch of the scream as he falls should be A) higher than the original pitch and increasing as he falls. By higher than the original pitch and constant. G lower than the original pitch and constant. Dj lower than the original pitch and decreasing as he falls. E) It is impossible to predict. 15) A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii. If the three of them are released simultaneously at the top of an inclined plane and do not slip, which one will reach the bottom first? A) pipe B) cylinder C sphere D) The pipe and cylinder arrive together before the sphere. E) They all reach the bottom at the same time