what is atmospjeric pressure and what is it caused by????
Rahul0110:
hiii
varshini roy
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the pressure exerts by the weight of the atmosphere , which at sea levels has mean value 101,325 pascal
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atmospheric pressure is defined as the pressure exterted by the atmosphere or it may be also called pressure exterted by the weight of the air column.
First of all, you have to know what is air pressure.
Our atmospheric pressure is 101325 Nm−2m−2. Consider a 1 m2m2 area. Now consider an imaginary column above the area that goes as high as the atmosphere. All the air in this column has a weight, right? And that weight happens to be 101325N.
So, pressure on something is nothing but the weight of the air above it. Gravity keeps the pressure of the atmosphere.
Now you have to understand another concept. Why does air fill vacuum?
Suppose you have a box. It has no air inside it. So there is a vacuum inside it. Now make a hole on it. What would happen? Air outside will fill the vacuum. This happens because air outside exerts a pressure on the box and flows in the box.
Now the pressure of air on the earth is towards the earth, not towards the space. So there is no force acting on the atmosphere that will make the air spread out to space.The gravity pulls the atmosphere and the atmosphere sticks to the earth. The vacuum in space is not like the vacuum in the box. So there is no reason for the air to spread out.
Gravity prevents the atmosphere from spreading out.
First of all, you have to know what is air pressure.
Our atmospheric pressure is 101325 Nm−2m−2. Consider a 1 m2m2 area. Now consider an imaginary column above the area that goes as high as the atmosphere. All the air in this column has a weight, right? And that weight happens to be 101325N.
So, pressure on something is nothing but the weight of the air above it. Gravity keeps the pressure of the atmosphere.
Now you have to understand another concept. Why does air fill vacuum?
Suppose you have a box. It has no air inside it. So there is a vacuum inside it. Now make a hole on it. What would happen? Air outside will fill the vacuum. This happens because air outside exerts a pressure on the box and flows in the box.
Now the pressure of air on the earth is towards the earth, not towards the space. So there is no force acting on the atmosphere that will make the air spread out to space.The gravity pulls the atmosphere and the atmosphere sticks to the earth. The vacuum in space is not like the vacuum in the box. So there is no reason for the air to spread out.
Gravity prevents the atmosphere from spreading out.
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