# Tag Info

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Moving bodies have inertia which means that they will continue to move at a constant velocity unless acted upon by an external force (this is Newton's first law of motion). Similarly, rotating bodies have a moment of inertia, meaning that they will continue to rotate unless acted upon by an external force (torque). Therefore, torque is only required to ...

1

By definition, work is $$W[\gamma] = \int_\gamma\mathbf F\cdot\mathbf v\text dt$$ i.e. force times displacement. If an object is not moving, even if subjected to a force, then there is no work done by said force. Observe that, since the object is not moving, the sum of all the forces applied to a body must be zero. For example, a body on rest on a table is ...

1

Work= force x displacement force is weight and displacement is 0 so there is no work (in physics)

0

As stated in the other answers (and your own question), mass and weight (downward force due to gravity) are two distinctly different units, but related via acceleration. So, in the presence of a gravity field such as we experience on the surface of the Earth, it can be convenient and more-or-less reliable to measure the weight of a thing to determine its ...

1

Actually when we measure our weight in a weighing machine, it is a big confusion that it is our mass or weight, because it measures in kg, which is unit of mass. But weighing machine measures our weight and its unit is in kgf (kilogram force) not kg, its a metric unit of weight, and as we know that N (Newton) is a SI unit of weight and 1Kgf = 9.807N So as ...

1

Yes, the moon does rotate. In a tidally locked system, the angular speed of the rotation of the satellite about its own axis is equal to the angular speed of the rotation of the satellite about its primary. Thus, the moon has an angular speed about the Earth of 1 cycle / 28 days, and an angular speed of 1 rotation / 28 days about its own axis; this is why ...

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I would like to add that on Jupiter bands are more evidente because the rotational speed of the planet is much bigger. Jupiter has a rotation period of about 11 hours and a radius 12 times that of earth.

3

Here's an interesting thought experiment. Imagine you have an elevator shaft to the centre of the Earth which, for some strange reason, doesn't affect the gravitational field of the Earth and doesn't flood with magma. OK, now at the Earth's surface get a bottle, half full with oil and half full with water. The water is denser than the oil, so the force ...

1

I will try to make a very approximate answer for your mother (as requested), assuming the Earth spherical, and several other approximations. I am no expert in geophysics, or stellar physics. and if you want details or greater accuracy, I suggest you look at other answers, such as that of David Hammen and others. About gravity First regarding gravity. Is ...

0

Take a glass of water and two small balls, same size, one of iron and one of aluminum. Both will reach the bottom finally, but because of buoyancy the iron will settle first. The Earth was discovered to have a solid inner core distinct from its liquid outer core in 1936, ..... It is believed to consist primarily of an iron–nickel alloy and to be ...

21

Forget about force. Force is a bit much irrelevant here. The answer to this question lies in energy, thermodynamics, pressure, temperature, chemistry, and stellar physics. Potential energy and force go hand in hand. The gravitational force at some point inside the Earth is the rate at which gravitational potential energy changes with respect to distance. ...

11

There are two different quantities here to distinguish: the gravitational force and the gravitational well. At the center of the Earth, the gravitational force is zero, but the gravitational well is at its deepest. The heavy elements tend to migrate to the lowest point in the gravitational well, so they are at the center, even though the force is zero there. ...

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I'm just 14, and I will try to answer the question based upon my understanding. First of all, gravity, being a force and thus a vector, would cancel out in the core, as it not only depends upon the magnitude of the relative force but also the direction of it i.e. a vector going upward would cancel out with a vector going downward, and so on. But..... If we ...

0

This is what tidal power generators do - if earth did not rotate relative to the moon, there would be no lunar tidal motion (there would be a distortion of the earth's equipotential surface but it would not move). Since earth does rotate, you get motion of the oceans. At Fundy Bay, for example, significant power is extracted from this motion. See ...

2

When you say you don't know your latitude - then why don't you measure that first? Measure the maximum altitude of the same (assumed very distant) astronomical object from two different places on the Earth's surface on the same day of the year. Measure the length between the two places. The method was used by Eratosthenes. A variant, used by Islamic ...

2

If you want to do it in 1 million years then your basic problem is kinetic energy. The gravitational potential energy of the Earth around the Sun is $-GM_{\odot}M_{E}/(1au) = -5.3\times 10^{33}$ J. To get to Proxima Centauri within 1 million years requires a relative velocity of at least 1.27 km/s. So I'm not sure how exact an answer you need. The main ...

3

Some rough estimates (you can dig up more accurate numbers): The oceans contain about 321 million cubic miles of water (source: http://oceanservice.noaa.gov/facts/oceanwater.html), or 3.5e20 U.S. gal. 1 gal seawater contains roughly enough deuterium to provide the same energy as 300 gal of gasoline (maybe slightly less - that's the part for your homework!), ...

3

To expand on @Alfred's answer, The gravitational attraction from the Earth as you dig down into the Earth is due only to the mass of the Earth enclosed by the sphere defined by the radius that you are at (see the derivation of Gauss's theorem for a proof of this). Therefore, as you go further down into the Earth, the amount of mass that is pulling you ...

7

Why is the g=G∗M/R2 not working There are two regions to consider; the region outside the Earth and the region inside. The solution inside (non-zero mass density) and the solution outside (zero mass density) are different but must give the same value at the radius of the surface. Assuming a uniform mass density inside, the gravitational acceleration ...

3

There's all kinds of awesome and complicated stuff going on in that image... so let's look at a much simpler one to see what you mean (source): At the equator, the predominant wind direction is easterly, or opposite the direction of Earth rotation. Away from the equator, north of 30 degrees, the winds are primarily westerly, with the direction of ...

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The short answer is -- there are bands! They behave very similar to the bands on Jupiter, but are not as pronounced. And we don't have a really unappealing colored atmosphere to show us what the bands look like. Here is an example of what they look like (source): There are two bands along each side of the equator. Another set of bands starts 30 degrees ...

2

Yes there is a net charge on the earth; no you can't use that to generate energy. For a current to flow, charge has to be moved by an electric field. In the case of Earth, how do you propose to create a circuit to tap into this field? You could move a charge from the ground to the clouds - and maybe do a very small amount of work while moving it. But then ...

2

The flux of cosmic particles that is particles that come from outside our solar system is linked to the suns magnetic field; the suns field to a degree protects the earth from cosmic particles more so than the earths field. Our stars magnetic field has a large influence on shielding the earth from cosmic rays but the suns field is not a constant, it also ...

2

Yes, it will cause many things to become radioactive, carbon-14 being one example. The cosmic radiation itself may reach the ground so we have much more to worry than just carbon-14. One of the first large-scale phenomena you will see is global aurora caused by solar wind. Over time, solar wind will disrupt the ozone layer and destroy yet another shield ...

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