The car in the drawing is moving to the left at 35 m/s. The car's horn continuously emits a 2.20 × 102 Hz sound. The figure also shows the first two regions of compression of the emitted sound waves. The speed of sound is 343 m/s.
-How far does the car move in one period of the sound emitted from the horn?
A)0.08 m
B)0.16 m
C)8 m
D)16 m
E)35 m

Question

The car in the drawing is moving to the left at 35 m/s. The car's horn continuously emits a 2.20 × 102 Hz sound. The figure also shows the first two regions of compression of the emitted sound waves. The speed of sound is 343 m/s. 
-How far does the car move in one period of the sound emitted from the horn?
A)0.08 m 
B)0.16 m 
C)8 m 
D)16 m 
E)35 m

Quizplus · Accepted Answer

The frequency of the sound wave emitted from the horn is 2.20 × 102 Hz, which means that the wave completes 2.20 × 102 cycles in one second. Therefore, the time it takes for one cycle is:
T = 1/f = 1/(2.20 × 102) s

During this time, the car moves to the left at a speed of 35 m/s. Therefore, the distance moved by the car during one cycle is:
d = v × T = 35 m/s × 1/(2.20 × 102) s = 0.16 m

Therefore, the best answer is (B) 0.16 m.

The Car in the Drawing Is Moving to the Left