Increased intensity, increased return time, and increased perceived frequency.

Decreased intensity, increased return time, and increased perceived frequency.

Decreased intensity, decreased return time, and increased perceived frequency.

Increased intensity, decreased return time, and decreased perceived frequency.

Decreased intensity, increased return time, and decreased perceived frequency.

The bat emits short pulses of ultrasonic waves, which return as echoes after hitting objects in the environment, providing information about their dimensions, locations, and possible movements. This is due to the bat's sensitivity in detecting the time it takes for the echoes to return, as well as small variations in the frequencies and intensities of the ultrasonic pulses. These characteristics allow it to hunt small prey, even when they are in motion relative to it. Consider a one-dimensional situation in which a moth moves away in a straight and uniform motion from a resting bat. The distance and speed of the moth in the described situation would be detected by the bat's system through which changes in the characteristics of the ultrasonic pulses?

Physics

The bat uses echolocation to detect objects. When the moth moves away, the intensity of the echo decreases as the energy of the sound waves disperses over distance. The echo return time increases as the sound wave takes longer to travel to the moth and back. The perceived frequency decreases due to the Doppler effect, as the moth is moving away from the bat, making the sound waves appear to have a lower frequency to the bat. Therefore, the correct alternative is 'Decreased intensity, increased return time, and decreased perceived frequency.'

Question about Waves: Sound Intensity

Subject Physics

Physics

Source ENEM

ENEM

Topic Waves: Sound Intensity

Waves: Sound Intensity

Difficulty Hard

Hard

(ENEM 2016) - Question Hard of Physics