ill bet the earth weighs hundreds of pounds.. . may be even MORE.....? thankyou.....
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Yes, the mass of the earth was worked out by Henry Cavendish in 1798, and the mass of the moon about 100 years later.
@tham153: The earlier of these dates was 70 years AFTER Isaac Newton died. Newton worked out the basic equation of gravity, and knew it involved some constant which he named "G", but he did not know the actual value of "G" because no instruments at the time were sensitive enough to measure it. Without knowing "G" you cannot calculate the mass of the earth (or any other large gravitating body). Newton went to his grave not knowing the value of his own constant, and not knowing the mass of the earth or the moon.
What Cavendish did was measure the value of the constant "G" in a laboratory experiment, by directly measuring the gravitational attraction between two metal spheres. Once the value of "G" was known, he (or anybody) could apply Newton's gravity equation to measure the mass of the earth.
But that technique only works when you can observe the gravitational effect that the body has on other objects. That was easy in the case of the earth, because we can directly measure the force the earth exerts on bricks, etc. But it wasn't so easy in the case of the moon. People tried to estimate the moon's pull on the tides, but that is hard to measure. It wasn't until the late 1800's that people were accurately able to tell by how much the earth "wobbles" in response to the moon's gravity. Once that was done, they were able (with the additional help of Newton's equation) to tell how heavy the moon was.
@tham153: The earlier of these dates was 70 years AFTER Isaac Newton died. Newton worked out the basic equation of gravity, and knew it involved some constant which he named "G", but he did not know the actual value of "G" because no instruments at the time were sensitive enough to measure it. Without knowing "G" you cannot calculate the mass of the earth (or any other large gravitating body). Newton went to his grave not knowing the value of his own constant, and not knowing the mass of the earth or the moon.
What Cavendish did was measure the value of the constant "G" in a laboratory experiment, by directly measuring the gravitational attraction between two metal spheres. Once the value of "G" was known, he (or anybody) could apply Newton's gravity equation to measure the mass of the earth.
But that technique only works when you can observe the gravitational effect that the body has on other objects. That was easy in the case of the earth, because we can directly measure the force the earth exerts on bricks, etc. But it wasn't so easy in the case of the moon. People tried to estimate the moon's pull on the tides, but that is hard to measure. It wasn't until the late 1800's that people were accurately able to tell by how much the earth "wobbles" in response to the moon's gravity. Once that was done, they were able (with the additional help of Newton's equation) to tell how heavy the moon was.
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Not as tough as it sounds. There are equations that are only missing a few variables, so you can plug in numbers and out pops the mass of the Earth and Moon.
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Google it, or Yahoo search !
W=mg, weight=W. m=mass, g=gravitational constant.
But it is weight in what gravitational field ?
You meant mass ?
W=mg, weight=W. m=mass, g=gravitational constant.
But it is weight in what gravitational field ?
You meant mass ?
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Both were worked out by Isaac Newton over 300 years ago. The Earth weight about 6 quadrillion tons, and the Moon's mass is 1.2% that of the Eart
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As both are in space they weigh absolutely nothing.
There is a fundemental difference between weight and mass
There is a fundemental difference between weight and mass