A. Balloons can be filled with air.
C. Air has mass.
The frequency of the human ear canal is 2.92 kHz.
Explanation:
As the ear canal is like a tube with open at one end, the wavelength of sound passing through this tube will propagate 4 times its length of the tube. So wavelength of the sound wave will be equal to four times the length of the tube. Then the frequency can be easily determined by finding the ratio of velocity of sound to wavelength. As the velocity of sound is given as 339 m/s, then the wavelength of the sound wave propagating through the ear canal is
Wavelength=4*Length of the ear canal
As length of the ear canal is given as 2.9 cm, it should be converted into meter as follows:

Then the frequency is determined as
f=c/λ=339/0.116=2922 Hz=2.92 kHz.
So, the frequency of the human ear canal is 2.92 kHz.
Answer:

Explanation:
From the question we are told that
Angle of cable 2 
Weight of sculpture 
Generally the Tension from cable 2
is mathematically given by



Generally the Tension from Cable 1
is mathematically given by



<span>The longest wavelength within the visible spectrum is the red
light. The answer is letter C. It is called visible light because it is the
only light that can be seen by the human eye. Red light is the longest
wavelength around 620 to 750 nanometer. It is followed by orange which has a
wavelength of 590 t 620 nanometer. And then blue which has a wavelength of 450
to 495 nanometer. And the shortest wavelength is violet which has a wavelength
of 380 to 459 nanometer. </span>
<span>The
formation of the Solar System began 4.6 billion years ago with the
gravitational collapse of a small part of a giant molecular cloud. Most
of the collapsing mass collected in the center, forming the Sun, while
the rest flattened into a proto-planetary disk out of which the planets,
moons, asteroids, and other small Solar System bodies formed.
Hope it helped
</span>