<span>Amorphous silica has a density of about 2.2 g/cm3, whereas the density of crystalline quartz is 2.65 g/cm3
</span><span>The difference in densities is
The atoms in amorphous silica do not pack as efficiently in three dimensions as compared to the atoms in quartz.
hope it helps</span>
The total electrostatic force on charge A is 
Explanation:
The magnitude of the electrostatic force between two charges is given by Coulomb's law:
where:
is the Coulomb's constant
are the two charges
r is the separation between the two charges
Here we have three positively charged particles A,B and C, located at the following positions:

The magnitudes of the three charges are:

The force exerted by B on A is to the left (because the force between two positive charges is repulsive), and the force exerted by C on A is also to the left (also repulsive). Therefore, the net force on A is just the sum of the two forces exerted by charges B and C:

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Answer:
negative acceleration of 4m/s²
Explanation:
Given parameters:
Initial velocity = 66m/s
Final velocity = 26m/s
Time taken = 10s
Unknown:
Description of the acceleration = ?
Solution:
Acceleration is the rate of change of velocity with time.
It is mathematically expressed as;
acceleration =
v is the final velocity
u is the initial velocity
t is the time taken
Now insert the parameters and solve;
Acceleration =
= -4m/s²
So, we see a negative acceleration of 4m/s²