Except for climate which has changes over the eons.
Answer b protons and electrons
It does produce 'sound' ... a compression wave traveling through the air. But your ears don't hear a sound that's vibrating less than 20 or 30 times every second. If you could swing your pendulum that fast, you could hear the sound of its vibrations pushing the air around.
Frequency (f) = 500 hz (SI)
Velocity (V) = 1250 m/s (SI)
Wavelength (Lambda) = ? meters

If someone is underground, then therefore there is less planet/ground underneath them, so there would be less gravity. Gravity directly affects weight.