• Question: What is weaker the gravity of the earth or the electromagnetism of a human?

    Asked by ilyas_ to William on 15 Nov 2018.
    • Photo: William Glass

      William Glass answered on 15 Nov 2018: last edited 15 Nov 2018 1:32 pm


      Now that is a very interesting and thought provoking question! I’ll try my best to answer it! So gravity is the attractive force between two masses (let’s call them A and B). The force between them is determined by an equation that is called an “inverse square law”, this basically means that if you moved A away from B by x2 the original distance, the force would decrease by 1/4 of it’s original value, the force is also directly proportional to the product of their masses (i.e. multiplied together).

      Similarly the force between two (static) charged particles (let’s call those C and D) also follows this law, being directly proportional to the product of the two charges. Usually these charged particles would be protons (positively charged) and electrons (negatively charged), since these particles are VERY tiny, their mass is negligible and so the force of gravity isn’t that important. Similarly if we were to go to the other end of the scale, let’s say the Earth and the Sun then the mass is HUGE and so the contribution from any charges are negligible.

      Hopefully that makes sense? In regards to the human body, it’s hard to define. On the scale of a human clearly the force of gravity is dominant but if we zoomed into a cell or even smaller to a protein (and the atoms that make it) then electrostatics would play an important role, in my work I focus on proteins that are responsible for electrical impulses moving through cells.

      There certainly isn’t a clear answer but it’s a really great question!

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