C. Convection is the transfer of energy by the motion of a fluid. Fluids are by definition substances in which particles are able to flow. Hence the answer is c
Answer: D. A wave with a shorter wavelength is always faster than one with a longer wavelength
Explanation: "Imagine two sets of waves that have the same speed. <u><em>If one set has a longer wavelength, it will have a lower frequency (more time between waves). If the other set has a shorter wavelength, it will have a higher frequency</em></u> (less time between waves). Light moves even faster AND has shorter wavelengths."
Why it's not C: "The number of complete wavelengths in a given unit of time is called frequency (f). <em><u>As a wavelength increases in size, its frequency and energy (E) decrease</u></em>. From these equations you may realize that as the frequency increases, the wavelength gets shorter. As the frequency decreases, the wavelength gets longer."
Why it's not B: "The frequency does not change as the sound wave moves from one medium to another. Since the speed changes and the frequency does not, the wavelength must change."
Why it's not A: "Do loud sounds travel faster than soft sounds? No. Both travel at the same speed The speed depends on the medium it passes through. Louder sounds are simply sound waves with higher amplitude traveling at the same speed."
Answer:

Explanation:
Given that,
Radius of a spherical shell, r = 0.7 m
Torque acting on the shell, 
Angular acceleration of the shell, 
We need to find the rotational inertia of the shell about the axis of rotation. The relation between the torque and the angular acceleration is given by :

I is the rotational inertia of the shell

So, the rotational inertia of the shell is
.
Protons copy the number equal
Answer: 1000 Hz
Explanation:
You can calculate frequency by dividing velocity by wavelength
Frequency = velocity/wavelength
Find velocity first.
900 m/3 s = 300 m/s
Plug values in to find frequency.
F = (300 m/s)/0.3 m
F = 1000 Hz