Welcome to brain Stuff from house stuff works dot com where smart happens. Hi Am Marshall Brain With today's question how much does planet Earth weigh? It would be more proper to ask what is the mass of Planet Earth? The quick answer to that is approximately six times ten. To them, it weighs a lot. The interesting sub question is how did anyone figure that out? It's not like the planet steps onto a scale each morning before it
takes a shower. It turns out that you can calculate the mass of something if you know the magnitude of its gravitational pull. Any two masses have a gravitational attraction for one another. If you put two bowling balls near each other, they will attract one another Gravitationally, the attraction is extremely slight, but if your instruments are sensitive enough, you can measure that gravitational attraction that two bowling balls have on one an other. From that measurement, you could
determine the mass of the two objects. The same is true for two golf balls, but the attraction is even slighter because the amount of gravitational force depends on the mass of the objects. Newton showed that for spherical objects you can make the simplifying assumption that all of the objects mass is concentrated at the center of the sphere. He then came up with an equation that expresses the gravitational attraction that two spherical objects have on one another.
It's force equals the gravitational constant times the mass of the first object times the mass of the second object over the distance between the two objects squared. Assume that Earth is one of the masses and that a one kilogram sphere is the other. The force between them is nine point eight kilogram meters per second squared. We can calculate this force by dropping the one ram sphere and measuring acceleration that the Earth's gravitational field applies to it,
which is nine eight ms per second squared. The radius of the Earth is six million, four hundred thousand meters. If you plug all these values in and solve for M one, you find that the mass of the Earth is six times ten to Do you have any ideas or suggestions for this podcast? If so, please send me an email at podcast at how stuff works dot com.
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