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What if everyone on the Earth jumps at the same time?

 

There is a common saying, “You can move the mountains”, do you think that is possible?  In analogy, if the entire population on the earth jumps at the same time, will the Earth move?

‘A BIG NOOOOO’

Whatever the condition maybe, whether all the humans are distributed equally or gathered in a particular place on the blue planet, the Earth won’t experience any change.

Justifications:

1. Approximately we can calculate,

The human population on Earth = 7 billion.

Average mass of each person = 60 kg.

Total mass of the humans = 420 billion kilogram.

The mass of earth is approximately 6*10^24 kilogram.

The ratio of mass of humans to that of Earth = (4.2*10^11 / 6*10^24)  = 7*10^-14.

Which means the mass of humans is 7*10^-14 times the mass of Earth. We can compare this to an ant jumping on the football. The football won’t undergo any deformation.

 2. According to Newton’s III law, “Every action has an equal and opposite reaction”. For jumping you push the Earth, and the Earth pushes you back to the air. By Newton’s II law let us calculate the acceleration exhibited by Earth, we know that F = ma. Here ‘m’ is the mass of Earth which is a huge quantity. So when we consider a constant force for a massive object like Earth the acceleration exhibited is ridiculously small but it will not be zero. There won’t be any measurable shift (as in, less than the width of a hydrogen atom). To see a noticeable displacement, you will require the collision of Earth with a planet or an object of equal or greater mass than that of it.

What actually happens?

While everyone reaches the ground after a jump, huge energy will be dissipated in the form of sound, heat and shock waves.

The Earth is not a perfect rigid body. Being elastic this act won’t accelerate the Earth. Consider we are jumping on a ground (sand or mud), the deformation caused by it will travel only to few meters. If the same occurs on a rock, then the deformation will ripple to several meters. But these waves are feeble and are called as weak seismic waves. So this won’t create any earthquake and disturbance in ocean.

At any instant of time, local movements are caused by the humans and other objects on the Earth like  walking, motion of vehicles, mining, volcano eruption, etc, are called the ‘ambient vibrations’ and considered as noise on seismograph. So, this is not an unusual event for the Earth. 

 

 

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