How to Weigh the Earth

This video demonstrates how to determine the mass of the earth using some very simple equipment and a powerful mathematical expression. A century wide collaboration between Newton and Cavendish makes this possible. The video includes a discussion of Newton's universal law of gravitation and Cavendish's famous experiment that led to the determination of "G" the universal gravitational constant.

Category:

Education

Tags:

• Mathematics
• Newton
• Gravity
• Cavendish
• weigh
• the
• earth
• Universal
• Gravitational
• Constant
• philosophy

[managarm1349]

you need to make much more videos, such great content

[mattius999]

I heard that if you dig a very straight tunnel from the surface of the Earth, through the Earth (not necessarily through the centre of the Earth), to a another place on the surface of the Earth that, no matter how long or short this tunnel is, the journey from surface to surface would only take about 40 minutes, because of the Earth's gravitational pull.

Not really that relevant, but still interesting. :)

[ytkoekie2000]

interresting video! But I don't really understand one thing: How was cavendish able to determine the mass of the earth? He knew about the radius of the earth, the value of M1(the object) and he was able to measure whit what force the ball is attracted to the earth. But he didn't know the exact values of the gravitational constant and M2 (the earth). I hope someone will read my question and answer it... you never know.

[familyguy3313]

if i worked it out right its 5,780,000,000,000,000,000,000,­000,000 septillion KG.............:}

[Spyez]

@3Nex

Weighing the Earth and calculating how much it weighs is the same process. A simple household scale uses a mathematical algorithm to correctly display your weight.

[alain001]

@RandomAwe I stated g, not G ;-)

[3Nex]

this isnt weighting the earth, its calculating how much it weights.

[moestietabarnak]

hmm, kinda cheated, the scale is actually a force to mass converter tuned for earth gravity.

[RandomAwe]

@alain001 Congratuliminizations!

You have just stated acceleration due to gravity! :D

Not the Universal Gravitational Constant. :)

[alain001]

g = 9.81 m/s²

[bnghtz]

@PartVIII Greeks had used a deep hole and sunlight and triangle similarities to mesure the radius of the Earth ,-)