Jakarta –
Planet Earth holds everything from hard rocks and minerals to millions of species of living things. Can accommodate a lot of material and living creatures, how much does Earth weigh?
Science believes there is no single answer to that question. This answer is the same as the weight of humans on the Moon which turns out to be much lighter than at home, Earth does not only have one weight. The weight of the Earth depends on the gravitational force pulling it.
However, what scientists have determined over the centuries is the mass of the Earth, that is, its resistance to movement against applied forces. According to NASA, the mass of the Earth is 5.9722×1024 kilograms or about 13.1 septillion pounds. This amount is equivalent to about 13 quadrillion of Khafre’s pyramids in Egypt, which weigh about 10 billion pounds (4.8 billion kilograms).
The mass of the Earth fluctuates slightly due to the addition of space dust and gases escaping from the atmosphere. However, these small changes will not affect Earth for billions of years.
However, physicists around the world still do not agree on decimal numbers and arriving at the total number is not an easy task. Since it is impossible to measure the Earth, scientists have to triangulate its mass using other measurable objects.
Newton’s Law of Gravity
The first component is Isaac Newton’s law of universal gravitation, Stephan Schlamminger, a metrologist at the US National Institute of Standards and Technology, told Live Science. Everything that has mass also has a gravitational force, meaning that every two objects will always have a force between them.
Newton’s law of universal gravitation states that the gravitational force between two objects (F) can be determined by multiplying the masses of each object (m₁ and m₂), dividing by the distance between the centers of the objects squared (r²), then multiplying that number by the gravitational constant (G) , otherwise known as intrinsic gravitational force, or F=G((m₁*m₂)/r²).
Sir Isaac Newton’s law of universal gravitation (F=Gmm/r2) is an equation that states the force of attraction (F) of two masses (m) separated by a distance (r).
Using this equation, scientists can theoretically measure the mass of the Earth by measuring the planet’s gravitational force on an object on the Earth’s surface. But there was a problem: No one could find the gravitational constant.
Cavendish Experiment
Then, in 1797, physicist Henry Cavendish began what is known as the “Cavendish experiment.” Using an object called a torsion balance, which consisted of two rotating rods with lead balls attached to them, Cavendish found the magnitude of the gravitational force between the two sets by measuring the angle on the rods, which changed when the smaller ball was attracted to the rods. the greater one.
“His work was very original and had a huge impact at the time,” said John West, a physiologist at the University of California, San Diego.
Knowing the mass and distance between the spheres, Cavendish calculated that G = 6.74×10−11 m3 kg-1 s−2. The Data Committee of the International Science Council currently lists G as 6.67430 x 10-11 m3 kg-1 s-2, just a few decimal points away from the natural Cavendish number.
Scientists have since used G to calculate the mass of the Earth using other objects of known mass and arrived at the figure of 13.1 septillion pounds that we know today.
Different Results
Although it has been more than two centuries since Cavendish’s experiments, the torque balance method is still used today. However, Schlamminger emphasized that although Newton’s equations and torque balance are important tools, the resulting measurements are still subject to human error.
In the centuries since Cavendish’s experiment, different scientists have measured G (the gravitational constant) dozens of times, and each produced slightly different results. The numbers differ by only a thousandth of a decimal, but are enough to change the calculation of Earth’s mass.
Despite the frustration surrounding the G, Schlamminger doesn’t see the disparity in numbers as a bad thing.
“Sometimes, it’s the gaps that the universe gives us that we can exploit and gain a more scientific understanding,” he said.
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(nir/nwk)
2024-04-07 01:00:00
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