In Fig. 17-53, a point source S of sound waves lies near a reflecting wall AB . A sound detector D intercepts sound ray R 1 , traveling directly from S . It also intercepts sound ray R 2 that reflects from the wall such that the angle of incidence θ i is equal to the angle of reflection θ r . Assume that the reflection of sound by the wall causes a phase shift of 0.500 λ . If the distances are d 1 =2.50 m. d 2 = 20.0 m. and d 3 = 12.5 m. what are the (a) lowest and (b) second lowest frequency at which R 1 , and R 2 are in phase at D ? Figure 17-53 Problem 109.
In Fig. 17-53, a point source S of sound waves lies near a reflecting wall AB . A sound detector D intercepts sound ray R 1 , traveling directly from S . It also intercepts sound ray R 2 that reflects from the wall such that the angle of incidence θ i is equal to the angle of reflection θ r . Assume that the reflection of sound by the wall causes a phase shift of 0.500 λ . If the distances are d 1 =2.50 m. d 2 = 20.0 m. and d 3 = 12.5 m. what are the (a) lowest and (b) second lowest frequency at which R 1 , and R 2 are in phase at D ? Figure 17-53 Problem 109.
In Fig. 17-53, a point source S of sound waves lies near a reflecting wall AB. A sound detector D intercepts sound ray R1, traveling directly from S. It also intercepts sound ray R2 that reflects from the wall such that the angle of incidence θi is equal to the angle of reflection θr. Assume that the reflection of sound by the wall causes a phase shift of 0.500λ. If the distances are d1 =2.50 m. d2 = 20.0 m. and d3 = 12.5 m. what are the (a) lowest and (b) second lowest frequency at which R1, and R2 are in phase at D?
Part C
Find the height yi
from which the rock was launched.
Express your answer in meters to three significant figures.
Learning Goal:
To practice Problem-Solving Strategy 4.1 for projectile motion problems.
A rock thrown with speed 12.0 m/s and launch angle 30.0 ∘ (above the horizontal) travels a horizontal distance of d = 19.0 m before hitting the ground. From what height was the rock thrown? Use the value g = 9.800 m/s2 for the free-fall acceleration.
PROBLEM-SOLVING STRATEGY 4.1 Projectile motion problems
MODEL: Is it reasonable to ignore air resistance? If so, use the projectile motion model.
VISUALIZE: Establish a coordinate system with the x-axis horizontal and the y-axis vertical. Define symbols and identify what the problem is trying to find. For a launch at angle θ, the initial velocity components are vix=v0cosθ and viy=v0sinθ.
SOLVE: The acceleration is known: ax=0 and ay=−g. Thus, the problem becomes one of…
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