The ions are in fixed positions.
Explanation:
Ionic solids are poor conductors of electricity because their ions are fixed in position. Their ions are not free to move about. They are fixed in crystal lattices.
- For the conduction of electricity, compounds must possess free mobile electrons and moving ions in solution.
- Ionic compounds are formed by the electrostatic attraction between a metallic and non-metallic ion.
- They actually contain ions but their ions are locked up.
- They are not free to move about.
- Electrical conduction involves ion mobility.
- In molten and aqueous forms, they are able to conduct electricity because their ions are then mobile.
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The two fields were physical quantities are used in motion calculations are length and mass with time.
The physical quantity in a field is referred as every point in a particular space time.
<h3>
How physical quantities are used in motion calculations?</h3>
If we consider an object, the physical property of the object is considered as physical quantity and to measure that object is known as units. The Physical quantity can be classified as elemental physical quantity and derived physical quantity. Length, mass, time, etc.. are elemental physical quantity, momentum, density, acceleration, etc... are derived physical quantity. Only for charge and temperature the physical quantity will be less than zero.
Length, mass and time are the physical quantities used in motion calculations.
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We know that arc length (x(t)) is given with the following formula:

Where r is the radius of the barrel. We must keep in mind that as barrel rolls its radius decreases because less and less tape is left on it.
If we say that the thickness of the tape is D then with every full circle our radius shrinks by d. We can write this down mathematically:

When we plug this back into the first equation we get:

We must solve this quadratic equation.
The final solution is:

It is rather complicated solution. If we asume that the tape has no thickness we get simply:
Vector it always consists to size(magnitude) and direction
Answer:
allow the downward movement of the concentration gradient by passive transport
Explanation:
Passive transport is a process of substance transport, which is carried out spontaneously, without energy expenditure and in favor of the concentration gradient, that is, from a medium where the molecules are more concentrated towards a medium where their concentration is lower.
Three types of passive transport are distinguished: osmosis, simple diffusion and facilitated diffusion
<u>Simple diffusion</u>
It is the passage, through the plasma membrane, of small molecules without charge soluble in the lipid bilayer, such as some gases (oxygen and carbon dioxide). For a molecule to diffuse through the membrane it is necessary that there is a difference in concentration between the external and the internal environment.
<u>Diffusion facilitated
</u>
There are molecules such as amino acids, glucose and small ions that, due to their chemical and size characteristics, cannot diffuse through the lipid bilayer and require transport proteins for diffusion.
The transport proteins are immersed in the plasma membrane and can be of two types: protein channels, formed by proteins that generate a channel in the membrane, and permeases, which are proteins that, when joined to the molecule to be transported, change their shape by carrying them into the cell.