Answer:
decibels (dB)
Explanation:
The sound intensity level is a quantity derived from the sound intensity.
The intensity of a wave is defined as the power of the source of the wave divided by the area through which the power of the wave is spread, mathematically:

where
P is the power of the source
is the surface area over which the wave spreads (assuming that the wave propagates in all directions, it corresponds to the surface area of a sphere of radius
, where r is the distance between the source of the wave and the observer)
For sound waves, the intensity is often expressed using another unit, called decibel (dB), defined as follows:

where
is the sound intensity level in decibels
I is the intensity of the sound wave
is the threshold intensity of a sound that a person can normally hear.
Answer:
The hummingbird travels the total distance is 10 m
Explanation:
Given that,
A hummingbird flies forward and backward.
According to figure,
We know that,
The total distance is equal to the sum of all distance.
Forward direction is positive and backward direction is negative.
We need to calculate the hummingbird travels the total distance
Using figure,

Put the value into the formula


Hence, The hummingbird travels the total distance is 10 m.
Merkel cells are the sensory receptors for touch.