Answer:
Hematite and magnetite
Explanation:
Minerals such as Iron don’t occur alone due to its interaction with other elements. The Iron’s major source is usually through ores such as Hematite, Magnetite, limonite etc.
However Pure magnetite contains 72.4 percent iron and pure hematite contains 69.9 percent. They have the highest percentage of iron thereby making them the main sources.
Twice the amplitude of each wave
-- 'Ca' (Calcium) is an element.
-- The proton has a positive charge.
-- Nuclear fusion results in the synthesis of atoms of new elements.
-- H₂O (water) is a chemical compound.
-- Nuclear fission is a decay of the nucleus.
-- The atomic number of an element is the number of protons
in each atom of it.
-- I suppose you're using the Greek letter <span>η ('eta', not 'nu')
to represent the neutron.
-- I suppose you're using ' e ' to represent the electron.
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Answer:
Sound is produced when an object vibrates, creating a pressure wave.
Explanation:
This pressure wave causes particles in the surrounding medium (air, water, or solid) to have vibrational motion. ... The human ear detects sound waves when vibrating air particles vibrate small parts within the ear.
To solve this problem it is necessary to apply the concepts related to the kinematic equations of movement description, which determine the velocity, such as the displacement of a particle as a function of time, that is to say

Where,
x = Displacement
v = Velocity
t = Time
Our values are given as,


Replacing we have that,



Therefore the distance from Earth to the Moon is 399.000 km