All Questions
Tagged with earth homework-and-exercises
74
questions
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Centre of Gravity of Earth-Moon Elevator [closed]
Suppose you have a cylindrical elevator that resembles a rod of mass $m$, cross-sectional area $A$ and uniform density $\rho$, with a length $L$ spanning the distance between the Earth and the Moon. ...
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1
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53
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At which colatitude $\theta$ is the error between $\vec g_{eff}$ and $\vec g$ maximum? [closed]
Suppose a plumb bob hangs without swinging, then the string defines the
effective direction of gravity. Suppose you are holding the bob on the surface of the
earth at colatitude $\theta$, where $\...
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1
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45
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Alfven waves in the ionosphere
I was given the following problem/question as a part of my homework in physics:
It is raining with thunder in Australia, and the lightnings generate transverse Alfven waves in the ionospheric plasma. ...
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2
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171
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Would a body have any residual velocity if launched at escape velocity from the Earth's surface?
A body is lanuched at escape velocity from the Earth's surface i.e 11.2 km/s ,what would be it's velocity outside the Earth's gravitational field?
I guess it would be zero but there's another problem ...
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0
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463
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How much time dilation are we experiencing here on Earth? [duplicate]
We experience time dilation from speed and gravity, but we are in more than just the Earth's gravity field, but also the sun's and the galaxy's gravity field and we are both spinning at 1,670 km/h, ...
0
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1
answer
127
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Problem on Angle of declination [closed]
There was a problem in my book that read- A magnet is pointing towards geographic north at a place where the horizontal component of the Earth's magnetic field is 40 microtesla. Magnetic dipole ...
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2
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375
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Calculate Earth angular speed [closed]
How may I calculate Earth's angular speed at specific point (The green dot for example)?
Note: I know that angular speed $= \dfrac{2\pi}{T}$ But how may I found $T$ in this case?
I found too that $R_{\...
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-2
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How high can you jump (at the corner) on Cube-Earth?
I have read this question:
Is the force of gravity always directed towards the center of mass?
And G. Smith's answer lists a site where they specifically talk about this case mathematically.
https:/...
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1
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1
answer
107
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Deriving gravitational acceleration from the formula for the force of gravity [closed]
I'm trying to derive this $g = 9.8 m/s^2$ from this
$$F = G\frac{m_E\cdot m_2}{(r)^2}$$
So I did:
$$g = G \frac{(5.972\cdot 10^{24}kg)}{(6.371km)^2} \Leftrightarrow \\
g = 6.67\cdot10^{-11}Nm^2/kg^...
0
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1
answer
104
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Black hole on Earth, 1 foot in diameter [duplicate]
If a black hole 12 inches in diameter were situated (say) 10 metres off the ground, what would happen?
And how long would it take to devour the earth?
user102490
4
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0
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685
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Determine Earth's radius with stopwatch at sunset [closed]
This question appeared on Bangladesh physics Olympiad 2014, Sylhet, Bangladesh for students of class 9 and 10.
I really tried to solve this, but I failed. Please help.
Suppose that, while lying on ...
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1
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0
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91
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Earth's surface area
Here we are trying to calculate the earth's surface area via geodetic coordinates:
\begin{align}
x&=(R\,p(\lambda)+h)\sin\lambda\,\cos\phi\\
y&=(R\,p(\lambda)+h)\sin\lambda\,\sin\phi\\
z&...
- 111
0
votes
1
answer
49
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How fast would an object at cruising altitude (around 10,600 m) need to travel to stay on the opposite side of the Earth to the Moon? [closed]
I am trying to figure out how fast an object will have to travel (at a height around 10,600 m) to never be in the presence of the moon. Meaning the object will always be on the opposite side of the ...
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2
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1
answer
102
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How much does NASCAR affect the rotation of the Earth? [duplicate]
Many of us will be familiar with XKCD 162: Angular Momentum, in which someone spins counterclockwise to slow down the rotation of the earth and make the night longer.
The mass of an individual human ...
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4
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What is acceleration due to gravity at the centre of the earth? [duplicate]
When I asked my teacher that what is the acceleration at the centre of earth, he replied that it is 0 as when we move inside the earth, the effective mass decreases i.e. the mass that exerts ...
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1
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Could enough people spin Earth backwards faster than they could run? [duplicate]
So, consider the theoretical situation in which the earth is no longer spinning, and we want to spin it up by running in the opposite direction (Yes, this question was inspired by the Nike commercial)....
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1
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1k
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Using energy method to solve SHM of an object through a tunnel dug through the Earth [closed]
I want to figure out the time period when an object performs simple harmonic motion by passing through a hole through the Earth.
Let the mass of Earth be $M_0$. Therefore, mass of Earth at radius $r$ ...
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1
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1
answer
386
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How can I obtain the position of the Earth on the orbit for given date?
I would like to be able calculate (or at least download some time-series data of) the position of the Earth on it's orbit at given date. For my purposes, it would be sufficient to account for the ...
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4
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Question about spinning Earth
The earth spins on its axis at 1674 km/h from west to east. Would it not imply that an airplane flying eastbound at 500 km/h would cover a distance of 500 kilometres in an hour while another plane ...
Saurav
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1
answer
88
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Constant of integration in Equilibrium Theory of Tides
I am preparing an elementary derivation of Newton/Laplace's equilibrium theory of tides.
The derivation of the tractive force is understood, as is the derivation of the differential equation for ...
0
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1
answer
258
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Will a projectile fired straight up from the equator land at the same spot on the ground ignoring wind? [duplicate]
Suppose a bullet were to be fired with a velocity $v$ from the surface at equator. Considering the spin of Earth will it land at the same spot?
I tried to solve this assuming constant acceleration ...
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2
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How to arrive to / calculate gravitational acceleration on Earth?
What are the exact steps and figures to calculate gravitational acceleration on Earth (9.8 m/s^2) and where do these figures come from?
(Please use an algebraic explanation, but assume understanding ...
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2
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1
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413
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The speed of throwing an object horizontally such that it is in orbit around the Earth [closed]
The question is given that for every 3,570 meters you walk , the Earth curves downward by 1 meter.
The time it takes an object to fall from a height h is
t = sqrt(2h/g), where t is in seconds, h is ...
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2
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393
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Can we feel weightless if Earth's angular velocity is big enough? [duplicate]
According to Fn=Fg-Fc , if earth's angular velocity is big enough to make Fc equal to Fg, would we feel weightless?
I did some basic calculation earth has to rotate at 1 rev/5064s at equator for Fc to ...
4
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2
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296
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How much mass must Earth lose to lose its Moon?
Maybe I am wrong about the basic concept here, but for my curiosity: how much mass would need to leave the Earth (like satellites and rockets) to create an imbalance between the Earth and Moon so that ...
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2
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417
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Proportional acceleration due to changing density of the Earth
My question has to to do with a recent video Minutephysics posted about the time it takes for a person to fall through the earth, found here
http://www.youtube.com/watch?v=urQCmMiHKQk
At around 4:05,...
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1
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572
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Calculating the Velocity of an object far far away
I saw a satellite the other day, it moved very fast through the night sky.
Now I know it took around 110 seconds for it to fully travel out of the night sky(out of my visual bounds assuming, that I'...
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3
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Can humans control rotation of the Earth?
I'm a class 12th student and this thought just struck me from nowhere.
Assume a situation where every human on this planet turns towards west. All of them start walking simultaneously in west ...
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1
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If the Earth were a pool ball, could I feel mountains? [closed]
If the earth (12,742 km diameter) were scaled down to the size of a pool ball (61mm diameter), the mountain ranges would still exist, obviously. But would a typical human be able to feel those ...
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1
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347
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How destructive would a small black hole be on the surface of the Earth?
Say a black hole with the diameter of around 200 meters or so was formed on the Earth's surface, how much damage would it cause?
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0
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Rotation of earth and effect on $g$ [duplicate]
How do we calculate the change in the acceleration due to gravity (consider earth as a uniform sphere) with a change in the rotation speed of earth along its axis?
How do we build up a mathematical ...
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2
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2k
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What exactly will happen if a small planet collides with Earth?
This is a video of a simulation of Ceres (a dwarf planet) hitting Earth at 2000km/s.
What strikes me the most, is how fast the shockwave is moving. It takes about 6 minutes for the shockwave to pass ...
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3
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2k
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Are we increasing the gravity of Earth with our population?
I have these questions related to my question title:
Do we, other species and things have our own gravity?
How much Gs a human have?
Are we effecting Earth, nearby moons and planets with our gravity?
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1
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How much radiation does the Earth receive from the Sun's total radiation? [closed]
I was thinking how to solve this problem. $1\,\mathrm{AU}$ is roughly the distance from the Earth to the Sun, $1.4960 \times 10^{11}\,\mathrm{m}$.
The radius of Earth is approximately $6.4 \times 10^{...
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4
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250
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Does not the mass of those living on the Earth add on to the mass of the Earth or is it too negligible to be cared for?
Source: Earth weighs about 13,170,000,000,000,000,000,000,000 pounds (or
5,974,000,000,000,000,000,000,000 kilograms). Since Earth is too big
to be placed on a scale, scientists use mathematics ...
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3
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2
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299
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Reaction due to gravity
There is a reaction to the gravity of the earth on us but the earth does not move due to its huge mass. But what if I combine the weight of all humans and other things on Earth? Is it not enough to ...
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How long will it take before the orbit of the earth is 365 days exactly?
I understand that the number of days per year has changed throughout the history of the Earth. Apparently there were once over 400 days per trip around the sun.
How long will it take approximately ...
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1
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216
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Centrifugal force on objects rotating around Earth
Suppose two objects travel around the equator on Earth at the same speed, $v$, in opposite directions, where the speed $v$ is measured relative to the Earth's surface. Will they experience different ...
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1
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2
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257
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Reduction of Earth's rotation due to increase in humidity
I came to know that, moon is moving away from earth, resulting reduction of Earth's rotation. Similarly, if Earth's humidity increases, water vapor will be move up to the air from water sources, will ...
-1
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1
answer
500
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Motion of a ball in a tunnel along Earth's diameter [closed]
Suppose, a tunnel is made along the diameter of Earth and we drop a ball inside it. How will the ball behave? Please help me understand.
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1
answer
2k
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How much energy would it take to stop Earth's rotation on its axis?
I see a lot of questions regarding situations what would happen if the world would stop spinning. This got me to wondering how much energy it would actually take to stop the world from spinning.
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How much time would it take for a free-falling ghost-like object to cross the entire Earth? [duplicate]
We have an object of mass $m$ which can go through matter like a ghost. It's only affected by gravity, not by any other force, so it's in free fall.
At the instant $t=0$ it is at the surface of the ...
- 1,613
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1
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2k
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How much potential fusion energy is in Earth's ocean?
Assuming the most efficient manner for extraction, and a ready supply of other necessary materials not mentioned herein, and given the current estimates about the volume of Earth's ocean, how much ...
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1
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365
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How much energy would it require to send Earth to Proxima Centauri?
Assuming 100% efficiency of energy usage, and given the current estimates about the mass of known objects in our solar system, including Earth itself, and assuming no other objects are affected by ...
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2
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2k
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How does the Moon cause the tides?
I am considering the following question, but I can't quite figure it out...
I have looked up differential gravity, but I cannot derive the equation for the effect on Earth, and I haven't found any ...
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3
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226
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How much additional light does Earth receive from the Sun due to Earth's gravitational field?
I was reading about how gravity affects light, and that got me wondering how much additional light is collected by the Sun due to the Earth's gravitational field.
Is it a significant amount of light (...
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2
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289
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If earth stopped spinning how much heavier would 1kg feel [closed]
My girlfriend seems to think if the earth stops spinning we will all fall off
However, she did spark my imagination, due to centripetal force things must feel lighter then they otherwise would on an ...
user68437
-3
votes
1
answer
115
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Physics Riddle - Know Plant Earth [closed]
I hope it's OK to ask here, because it's pretty much as basic as physics can get. So here it is:
I have a hot air balloon that can rise to any altitude I'd like, a precise watch, a sandbag, a weigh ...
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1
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59
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Why do we have to use an integral in this scenario to figure out $v_{max}$? [duplicate]
$$\int_0^R mg\frac{r}{2}dr=\frac{m}{2}v_{max}$$ and can't write $$\frac{m}{2}v_{max}=mgR$$ don't we usually equal potential energy to kinetic energy?
A stone is falling through a tunnel towards the ...
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1
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453
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How much effort would be required to fix the Earth's rotation?
Given that the earth's rotation has been slowing down by very slight amounts over time, forcing us to introduce leap seconds and so forth into our clocks and calendars, I would like to ask if this ...
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