• Question: How much does the earth weigh?

    Asked by anon-256753 on 9 Jun 2020.
    • Photo: Ricardo González-Gil

      Ricardo González-Gil answered on 9 Jun 2020: last edited 9 Jun 2020 10:41 am

      Hi Adam! Not really my field, but I can try to give you an answer. I think what you really mean is, “What is the mass of the Earth?”. Weight and mass are different; Mass is the amount of matter that there is in a body while weight is how much the force of gravity acts upon the mass of a body. The mass never changes, but the weight changes: you weigh less on the Moon than on Earth because Moon’s gravity is weaker. But your mass is always the same (check this link: https://www.thoughtco.com/mass-and-weight-differences-606116#:~:text=The%20difference%20between%20mass%20and,of%20matter%20in%20a%20body.&text=Weight%20usually%20is%20denoted%20by,acceleration%20of%20gravity%20(g).)

      The mass of the Earth is 6,000,000, 000,000,000,000,000,000 kilograms. Please check also this link for further details: https://science.howstuffworks.com/environmental/earth/geophysics/planet-earth-weigh.htm

    • Photo: Mary Gagen

      Mary Gagen answered on 9 Jun 2020:

      Fantastic question! We measure the weight of things in terms of their ‘mass’. There is a great answer on that from Ricardo here 🙂 …The mass of the Earth (6 and then 24 zero’s Kilograms) is really interesting because it tells us Earth is the densest of the ‘rocky’ inner planets. Our solar system is divided into the four rocky inner planets (Mercury, Venus, Earth and Mars), they’re rocky and dense and tend to have atmospheres of some sort, and then the outer gas giants (Jupiter, Saturn, Uranus and Neptune). These groups are hugely different, even though we tend to show them all bunched up together as one solar system. The inner rocky planets formed, close to our young sun, from grains of dust, then pebbles, then rocks, then big rocks, then really big rocks sticking together. It probably took tens of millions of years for the rocky inner planets to grow to their current size and mass. Something else interesting about Earth’s ‘weight’ is that it is not the same everywhere! The mass of the core is higher than the mass of the crust. The Earth’s mass is important becuase it defines our gravitational pull as 9.8 metres per second (which we call 1 g).

    • Photo: Richard Palin

      Richard Palin answered on 9 Jun 2020:

      This is a really interesting question that demonstrates the difference between mass and weight. Mass measures the amount of matter in an object and weight is the force of gravity on an object. Weight is calculated by multiplying your mass by the acceleration of gravity. For example, on Earth, your body might have a mass of 70 kg and you have a weight of (70 x 9.81) Newtons. However, on Mars, which is smaller than Earth and so has a weaker gravitational attraction, your mass would be the same but you would weigh about three times less.

      So, asking how much the Earth weighs isn’t easy to answer – what is the force of gravity acting on the Earth as a whole? It’s easier to state how much mass the Earth has, which is around 6 x 10^24 kg.

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