Have you have wondered that why balloons pop when you take them to mountains or any higher altitudes? Or why an unpacked bag of snacks becomes inflated and popped at times as you go up hill. The answer lies in the change of something called atmospheric air pressure.
Even though we can’t see or feel the atmospheric pressure in everyday situations but in reality atmospheric pressure is incredibly strong. The atmospheric pressure at the surface of the Earth (sea level) is 1 atm or 14.70 psi (pound per square inch).
1 pound is about 0.45 kg which means that if you put 14.70 x 0.45 = 6.615 kg of mass in an area of 1 sq. inch then that’s the atmospheric pressure at Earth surface.
If the atmospheric pressure is so strong then why we can’t feel its force?
Well, this is because our bodies internal pressure is also same as atmospheric pressure which means that outward pressure of atmospheric air is cancelled out by our body’s internal pressure. We feel no net force.
However some birds and insects, are amazingly perceptive of feeling changes in atmospheric pressure. That’s how they know when bad weather is coming or when it’s time to migrate to another region when winter is started.
Atmospheric pressure decreases as you move up to higher altitudes. So that’s the reason why when you blow a balloon and then take this balloon high in the mountains . The atmospheric pressure outside of balloon becomes lower as compare to inside of the balloon, therefore the net force is acted on the balloon in outward which causes it sometime to pop.
There is an experiment known as Magdeburg Experiment which can demonstrate the strength of atmospheric pressure.
Magdeburg Experiment – Demonstrating the strength of Atmospheric Pressure?
How atmospheric pressure exerts force on the objects were demonstrated by Otto von Guericke in 1864 in his famous experiment known as Magdeburg experiment as it was performed in the German city of Magdeburg.
The original experiment involved two large copper hemispheres, each with a diameter of about 50 cm, that could be fitted together to create a hollow sphere. After the two hemispheres were fitted together, the air inside was evacuated using a pump, creating a vacuum inside the sphere. When the air was removed, the external atmospheric pressure pushed the hemispheres together with great force, creating a strong seal. The most famous part of the demonstration involved connecting a team of horses to each hemisphere. They would try to pull the hemispheres apart, but the atmospheric pressure pushing them together made it impossible to separate them. This dramatic display of the force of atmospheric pressure became a classic demonstration in the study of physics.
Magdeburg experiment can be demonstrated by the small kit as shown in the following picture:
This educational kit is a miniaturization of Magdeburg experiment. This kit is sold in loose form as shown below.
Follow the following steps to perform the experiment:
- Assemble the kit as show below :
2. Once the kit is assembled, pull the plunger to remove the air from the spheres.
3. Now if you try to pull the spheres apart in opposite direction. You will find that no matter how hard you pull those spheres, you will not be able to detach them from each other. This is due to the reason that atmospheric force outside the sphere exerts a huge pressure since there is no force, inside the spheres, acting on the walls of sphere. Hence if try to pull apart the two spheres, the atmospheric force outside the sphere is much larger than the force exerted by us.
You can watch video how the above experiment works by clicking below: