All Questions
Tagged with newtonian-gravity reference-frames
228
questions
4
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4
answers
343
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What is the relationship between gravitation, centripetal and centrifugal force on the Earth?
I'm trying to analyze a situation wherein a ship is moving across the surface of the earth. I am trying to analyze this situation in a reference frame that is rotating with the earth (NED frame).
I am ...
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votes
3
answers
81
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Pseudo Orbital motion only due to Coriolis force
Planet, say of mass M and radius R is rotating with some angular velocity ω and a object of mass m (initially on the surface and rotating with the planet) was launched with velocity v vertically ...
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1
vote
1
answer
48
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Drawing a free-body diagram for a body residing on Lagrange point $L_4$ and $L_5$
I am aware of the fact that Lagrange points $L_4$ and $L_5$ are stable equilibrium points however I cannot understand why they are equilibrium points in the first place.
Consider a Earth-Moon system ...
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2
votes
3
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50
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Constant speed (at terminal velocity) and zero $g$
I have read the question What would a person experience in a free-falling elevator in a shaft long enough to reach terminal velocity? here and the answer was that you feel exactly the same if the ...
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1
vote
2
answers
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Centrifugal force has always been a nightmare to me
Suppose I'm in a rotating space station (that is somewhere in free space) and there is no other force. Now how am I supposed to fall to the circumference of the station if nothing pulls me? I will ...
0
votes
3
answers
173
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Gravitational force and centre of mass
So question goes like
"What is the magnitude of gravitation force of the particle due to rod?"
In the figure the particle is of mass $m$ and from distance $d$ from end of the rod and the ...
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votes
0
answers
79
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Do all bodies in a 3-body system orbit their center of mass with respect to each of the other bodies?
Scenario
Consider an empty universe with just the Earth, Moon and the Sun. The Earth and the Sun will rotate about their center of mass, which is inside the Sun. The Earth and the Moon will orbit ...
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0
answers
35
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So I've found out heavier objects technically do fall faster? [duplicate]
Given the Earth's mass to be $M_E$, I know that $F_G = -\frac{GM_Em}{d^2}$, so the gravitation acceleration of a mass towards Earth is $g = -\frac{GM_E}{d^2}$. But what about the force exerted by the ...
1
vote
2
answers
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Centripetal force on the surface of earth
Initially, I was looking for how centripetal force is produced on the surface of the rotating earth for a mass kept at any latitude. I went through the following threads -
Which force provides the ...
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votes
0
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76
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Two-body problem and motion in a central field
If we consider motion of a body in a central (gravitational) field the equation of motion would be
$$-\frac{\gamma m_1 m_2}{r^2}\frac{\vec{r}}{r}=m_1 \vec{r}^{\prime\prime}$$
where the origin of ...
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votes
2
answers
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How can people be weightless on space station?
I had read it somewhere that on the space station, people are weightless. even though artificial gravity is created there, people are still weightless. how can this be possible if there is gravity, ...
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14
votes
9
answers
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Is Earth really flattened at the poles because of centrifugal force?
My question is pretty much all in the title. I was always told that our planet is flattened at its poles due to the centrifugal force generated by its own rotation. However I don’t see how centrifugal ...
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1
answer
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How does a gas giant planet hold it's spherical shape when it has tidally locked rotation in it's orbit around the Sun?
How does a gas giant planet hold its spherical shape when it has a tidally locked rotation in its orbit around its Sun? Wouldn't it fall apart without its gravitational pull from the rotation? How ...
0
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0
answers
34
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How can we use Newton's laws in an accelerating frame? [duplicate]
This question is bothering me for a while. As far as I know, newton's laws are valid for any inertial or non-accelerating frame. Then how can we apply newton's law on earth where we are constantly ...
- 48
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1
answer
91
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Free falling elevator - A person would "levitate"? [duplicate]
If an elevator goes into free fall, assuming there's no friction or anything like that, would it actually float? From what I understand, this would only happen if the elevator falls with an ...
0
votes
1
answer
45
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Why don't we feel centripetal force as we move from the outside of orbit to the inside?
In a debate with a flat earth friend and need help to make sure I understand this correctly.
He points out that the part of earth that is on the outside of its orbit is traveling faster than the ...
1
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2
answers
77
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Why is it proclaimed for astronauts to be "falling"?
My physics teacher explained that the reason why it looks like astronauts are floating is because they are "falling". However, the way I think of it is that the outwards inertial force of ...
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1
answer
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Experiment to find the Center of Gravity under non-uniform $g$-field
When asked about how to find the center of gravity (CG) for a system, the answer normally goes like "suspend the system at different points and see how the vertical lines pass through. The CG is ...
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2
answers
278
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Equivalence of Center of Inertia and Center of mass [duplicate]
Why does center of gravity and center of mass correspond to the same point on the body only when gravitational field applied can be assumed to be constant?
Reference: IE Irodov, Fundamental laws of ...
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4
votes
3
answers
256
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Could you feel your weight falling through the a tube drilled through the center of the earth?
Suppose you drill a hole through the center of the earth (assume the earth is uniform and no air resistance) and you jump in. Would you be "weightless" throughout the entire fall?
The reason ...
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2
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Theoretical question about elevators [closed]
Question
Imagine we put a bascule/weighing machine in an elevator, and that elevator starts to acelerate downwards with a certain aceleration that we don't know of. Is it true that the bascule will ...
user348118
4
votes
3
answers
989
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Does the Coriolis force apply to an object moving weightlessly in a tunnel around the center of Earth?
I just want to be sure I understand correctly.
They ask us to find the speed at which an object moves weightlessly in a tunnel around the center of the Earth. Assume Earth is homogeneous, and the part ...
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Applied Example of Coriolis Force/ Effect for an Object Moving around Earth
There are very few examples on the Internet about how to calculate the Coriolis Force of an object moving around Earth.
Could you give me your feedback about how I proceeded ?
The Coriolis Force is ...
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2
answers
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How do Parabolic Flights exactly work?
I understand how one can feel weightless in an elevator - in the person's reference frame, they are not being pushed up by the floor.
However, I don't understand how this can occur in parabolic flight....
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3
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Does gravity cause the Earth's equatorial bulge?
The way I understand centrifugal force, I don't see how Earth's daily rotation alone would cause equatorial bulges to form. The usual explanation is that the centrifugal force increases with distance ...
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Is net gravitational force directed to the center of mass?
I have a question regarding the answer from this topic Is the force of gravity always directed towards the center of mass?
One of the answers states the following problem.
"Three spherically ...
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votes
2
answers
32
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Times of free-fall in different inertial reference frames in classical physics
Imagine that a ball is thrown directly down at a rate of 20 m/s from a height of 100m in Earth's gravitational field. If we were to calculate the time it takes to fall we could use the kinematic ...
0
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1
answer
47
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How we will choose reference point for more than two particle system to calculate potential energy as in the case of of equilateral triangle?
Suppose there are three mass, $m_1$, $m_2$, $m_3$. In the case of equilateral triangle we bring $m_1$ which has zero potential energy then we bring $m_2$ and consider $m_1$ and $m_2$ as one pair and ...
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The chronology of taking approximation changes the answer?
The problem is to find the time it takes a particle dropped from a height $h_0$ above the surface of the earth to reach the surface (exactly, not approximately i.e. $g$-value is not constant, in the ...
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If I hang from the ceiling of the elevator which is falling freely then will I experience weightlessness?
We all know that while the lift (or elevator) is accelerating downwards we feel less weight, now suppose I hang from the ceiling with the help of a stick in some cavity of the ceiling itself, then ...
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1
answer
79
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Simple Analytical mechanics problem [closed]
I am trying to solve a simple problem stated as follows:
"There are two cartesian reference frames k $(o;x,y,z)$ and K $(O;X,Y,Z)$ with the first one being still (inertial) and the second one (K)...
0
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1
answer
54
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Circular motion of planet around star
The question says that the planet moves in a circular orbit around the massive star. But the graph says that velocity of the star wrt the COM of star-planet system varies with time. But my confusion ...
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votes
1
answer
540
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Are orbital eccentricities in a binary system always the same?
Some excercises on Kepler laws and binary system use this relation $$\frac{r_1}{r_2} = \frac{a_1}{a_2},$$
where $r$ is the distance from the center of mass to each object and $a$ is the semi-major ...
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0
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58
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Separate the rotational acceleration from the gravity
I tried to plot the magnetometer and accelerometer readings: Fig1 and Fig2, respectively. The readings were collected by rotating the sensors around x,y,z axes. As you can see, the mag readings (Fig1) ...
0
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1
answer
102
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Where would the centre of gravity be for 4D shapes?
Say, hypothetically, we took a hypersphere where would the centre of gravity be for such an object.
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3
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What exactly will happen if you jump in the upward direction from a roof of on a moving car?
I'm not a physicist and I'm a little bit puzzled with the image below:
I know it's a joke but if we assume we don't have air resistance what exactly will happen if someone jump in the upward ...
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1
answer
79
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How does Lagrange point $L_2$ provide even meta-stability if centrifugal force isn't real?
I recall hearing, perhaps colloquially, that a centrifugal force doesn't exist. It can be mistakenly felt but, it is not a real force. Given this, how does the $L_2$ orbital point exist beyond the ...
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1
answer
224
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Gravitational forces of a building
In trying to understand the gravitational forces of a building, I have devised a thought experiment:
A building is floating in space. The building's mass is asymmetrically distributed. Inside it also ...
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1
answer
378
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Why do the 2 planets in a two-planet system orbit around the center of mass?
When reading the Feynman Lectures (chapter 7, volume 1), Feynman was explaining the formation of tides on the Earth and said the following:
The moon does not just go around the earth, the earth and ...
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1
answer
112
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What is the intuition behind excluding the effect of gravity from accelerometer data
In the unit of accelerometer and linear acceleration, I see that accelerometer is angular and the linear acceleration is linear. There is the impact of gravity on the accelerometer. However, ...
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2
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62
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Can the apparent weight in a elevator accelerating downwards be compared to that of body submerged in a fluid
Can the apparent weight of a person ( here I mean what a weighing scale would read if that person were to stand on it ) in a elevator going downwards( NOTE: the acceleration is less than the ...
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answer
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How can this contradiction be avoided and be corrected?
Suppose we have a situation with a massive planet and a rocket is sent from a height $h$ with speed $v$ greater than escape speed. Now initial angular momentum is finite as $mvh$, but as we know it ...
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2
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39
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Apparent weight in diurnal motion
An object of mass $m$ is on the equatorial plane. Now it is moving in a circle of radius equal to the radius of earth $R$. The object is moving with angular acceleration $\omega$. Let us observe from ...
- 1,179
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3
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579
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Two particles rotating about their center of mass
Two bodies each of mass $m$ are rotating about their center of mass where the radius is $r$.
Here centripetal force of each body is $\frac{mv^2}{r}$ where $v$ is the linear speed. Now, gravitational ...
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1
answer
2k
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What happens to a person in an elevator with a downward acceleration greater than $g$?
So I've been learning about the apparent weight of a person in an elevator accelerating upwards or downwards. I learnt that:
If it accelerates upwards with an acceleration a, Apparent weight = m (g+a)...
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1
answer
60
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Elevator situations
What happens to my weight when I'm in an elevator that's,
a. stationary
b. moving with a constant velocity
c. moving upwards with an acceleration a where a<g
d. moving upwards with an acceleration ...
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2
answers
120
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Who moves when an object falls by gravity? [duplicate]
I'm reading calculus book by Morris Kline. This book treats physics because calculus grew out of physical and geometrical problems. I have no background about physics and got a question while reading ...
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2
answers
81
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Gravity, forces, spacetime, acceleration conundrum
If gravity is not a force but rather spacetime curvature, why when standing on a scale do we say the "normal force" the actual force that the scale is measuring? Is the normal force caused ...
user232620
17
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7
answers
5k
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If centrifugal forces are fictitious, then isn't gravitational force also fictitious?
When the earth revolves around the sun, the sun attracts the earth by a gravitational force $F_{se}$ (centripetal force), and the earth attracts the sun by a gravitational force $F_{es}$ (centrifugal ...
- 1,018
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11
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Can a person on the equator jump up higher into the air at sunset than at sunrise?
I am wondering if a person on the equator can jump up slightly higher into the air at sunset in comparison to jumping up into the air at sunrise.
The reason for this would be that at sunset the Earth ...
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