The Newtonian model of gravity in which the force between two objects is given by GMm/r^2.

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How does artificial gravity reduction (weightlessness) work on Earth?

Some of us have been to those amusement park/carnival/theme park rides where you enter some capsule/machine, and you will float, etc. There is also some other thing where you go inside a big room ...
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4answers
114 views

Car driving / falling off of a cliff - will it land upright?

In a recent episode of The Walking Dead, a van was pushed off of a bridge and flipped once and landed upright, on all four wheels. Assumption: the ground and cliff are both flat. Will a vehicle ...
21
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5answers
6k views

Build a ring around Earth, then remove the supports

What would happen if we decided to build a giant ring that managed to wrap around the whole world, end to end that was supported with pillars all along the ring and then the supports all suddenly ...
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5answers
5k views

How fast would someone have to run to travel vertically up a wall?

I am currently doing a physics project on the effects of so-called 'super-speed'. I was wondering how fast you would have to run to vertically travel up a wall? That is, to negate the force of ...
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3answers
1k views

How accurately can I expect to measure the gravitational constant with a club of college students?

I am a math instructor with almost no experimental physics background, but I run a math and engineering club that is interested in doing some experiments. I have read up a bit and see some obvious ...
2
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1answer
71 views

Rate of acceleration for two hanging masses in two experiments

I conducted an experiment where two masses of different weight were attached by a string and fed through a pulley. The difference between the masses was $0.025\: \mathrm{kg}$. The lighter mass was ...
2
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2answers
986 views

What is the weight of the Philae lander on the Churyumov–Gerasimenko comet compared to earth?

We know the payload mass of the Philae lander was 21kg. We know the mass of the Churyumov–Gerasimenko comet is roughly 1 x 10^13kg. We know the mass of Earth is roughly 5.9x10^24kg. I've heard ...
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7answers
355 views

Distribution of Gravitational Force on a non-rotating oblate spheroid

Suppose a person is standing on a non-rotating oblate spheroid. He first stands on one of the poles, then on the equator. In which case is the gravitational force greater? In Case 1, the distance ...
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1answer
49 views

Newton's gravity formulas for ellipses

A few times I've come across formulas, which are identical for circular and elliptical orbits, except that for the second ones you substitute $r$ with $a$, where $r$ is the radius of a circular orbit ...
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0answers
20 views

Effect of Earth's rotation on apparent weight (acceleration due to gravity) [duplicate]

What would be reason for change in weight due to rotation of Earth? How can the direction of $g'$ (The value of $g$ at any point on Earth) be the apparent vertical direction? Why isn't $g$ the ...
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3answers
1k views

How the apparent weight varies due to the rotational motion of Earth?

I learned that as the earth rotates about its axis, the bodies on the earth also follow a circular path. In most books I read, they give the example of a person standing on a weight balance at the ...
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1answer
47 views

Direction of gravitational field in Hemisphere

Supposing we have a uniformly mass distributed hemisphere of some radius, so what will be direction of gravitational field throughout the flat surface of hemisphere? And why?
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1answer
432 views

Philae lander simulation off by factor of ~3

I'm trying to simulate the Philae landing by writing a program to compute the position of the lander vs time. According to various mission websites, the orbiter will match its orbit to the rotation of ...
3
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1answer
85 views

How would the Sun's gravity affect us if we weren't in orbit?

So since we're in orbit around the sun, we are basically in free-fall. From what I understand, this means that we don't feel the gravity of the Sun like we do the Earth. Just like astronauts on the ...
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4answers
2k views

How can I measure the mass of the Earth at home?

How can I measure the mass of the Earth at home? How was the mass of the Earth first measured?
3
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2answers
339 views

Platform diving: How deep does one go into the water?

I am a platform diver. I am trying to figure out how deep in the water I go depending on which platform I dive from. The platforms are 1m, 3m, 5m, 7.5m and 10m above the water surface. By ignoring ...
12
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4answers
743 views

Is it possible that 5 planets can revolve around a single star in a single orbit?

I'm writing a novel and I'm quite confused if this system could be possible in the real universe. Is it possible that a system exist, where 5 identical planets which could be of same characteristics ...
0
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1answer
68 views

Is there anything interesting about an n-body system whose potential energy is constant?

I am curious about a system of gravitating bodies with particular characteristics. Before describing the characteristics of the system, let me say what I want to know about it: Can this be a ...
0
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1answer
44 views

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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4answers
1k views

If you could ride an elevator through the earth [duplicate]

What if it was possible to ride an elevator straight through earth. If we take all the heat and pressure problems away, and assume it would be possible: What would happen with gravity? Would gravity ...
0
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2answers
40 views

Human between two bodies of large mass

What if a person is put between two identical dense spherical bodies (well, not as dense as black holes, but definitely 100 times more than earth) with mass $M_1=M_2=10^{30}kg$, exactly in the middle ...
1
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1answer
809 views

Calculating semi-major axis of binary stars from velocity, position and mass [closed]

I'm trying to calculate the 'instantaneous' semi-major axis of a binary system with two equal (known) mass stars for an $N$-body simulation. I know their velocities and positions at a given time, but ...
30
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5answers
5k views

Which ball touches the ground first?

This is a very well known problem, but I can't find an answer in the specific case I'm looking for. Let's consider two balls : Ball 1 weighs 10 kg Ball 2 weighs 1 kg Balls have identical volumes ...
5
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2answers
2k views

Calculating gravity when taking into account the change of gravitational force

This is a problem that has bothered me for a couple of weeks now, and I can't seem to wrap my head around it and understand it. Let's say we have a planet with a mass of m. We also have an object of ...
0
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3answers
149 views

How much does the Earth's population affect the force of gravity? [duplicate]

If everyone on earth except one person were to gather up in one location, say the North Pole, and jump at the exact same time and stay airborne for about 1.5 sec. And that one person who did not jump ...
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5answers
658 views

Why is kinetic energy stored as potential energy in a body during its motion against gravity?

Everyone knows kinetic energy is converted to potential energy in the body when it moves up against the earth's opposing gravitational force. But I am facing some problem with this. What I learnt ...
3
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2answers
114 views

Kepler's First Law of Planetary Motion: Whats at the other focus? [duplicate]

Kepler's first law states that the orbit of every planet is an ellipse with the Sun at one of the two foci. Is there anything significant about the location, or any unusual properties about the other ...
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5answers
5k views
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1answer
45 views

Projectile motion. Is there a point where sum of the forces is 0?

Body of mass m, is thrown with initial speed, at an angle α from a horizon. Neglecting wind resistance, is there a point on the trajectory where the sum of forces is 0? I don't think so, but maybe at ...
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1answer
60 views

Two-Body problem confusion regarding equations of motion

I'm reading John Taylor's Classical Mechanics text, and I'm a little confused about something in chapter 8, which deals with the two-body problem with central forces. The issue is with the equations ...
0
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1answer
89 views

Question regarding calculating acceleration due to gravity on planet Mercury [closed]

I was asked to calculate the acceleration due to gravity on planet Mercury, if the mas of Mercury is $2,99 \times 10^{22} kg $ and its radius is $2,42 \times 10^{3} \ km$. The mass of the object is ...
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1answer
126 views

Follow up question regarding: Deceleration rate of objects of different mass but the same otherwise

My first question was answered here: Deceleration rate of objects of different mass but the same otherwise . But based on that, here is a follow-up question (I also edited my first post with the ...
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4answers
2k views

Why do objects fall at the same acceleration?

I read these two posts and now I am more confused. Do heavier objects fall faster? Don't heavier objects actually fall faster because they exert their own gravity? I was going to ask: if mass ...
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1answer
142 views

how can an egg be balanced on a nailhead on equator [closed]

How can an egg be balanced on a nail head on equator? Why only on equator and not on different latitudes?
3
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2answers
184 views

What is the cause of planetary rotation. Not orbital rotation [closed]

I am a senior in high school, sixteen years old. I think differently than most in my class. Recently, I have been thinking about alternative causes for the rotation of our planets. My current thought ...
0
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2answers
873 views

Time taken for object in space to fall to earth

The Problem For a small mass a distance $R_i$ away from the center of the Earth, how long would it take for the object to fall to the surface of the Earth, assuming that the only force acting upon the ...
4
votes
3answers
782 views

Does gravity slow down a horizontally thrown baseball?

I have a simple question: Does gravity slow down a horizontally thrown baseball? Assuming when a baseball is thrown it has a vertical velocity as well, does it slow does the ball? Any help is much ...
0
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2answers
110 views

What is the jerk due to gravity with ascent? [closed]

Acceleration is defined as the rate of change of velocity with time. Jerk is defined as the rate of change of acceleration with time. What is the jerk due to gravity with ascent?
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2answers
75 views

Does a ball spin more from left to right than it does from right to left?

I swear that in a manual on tennis published by the German Tennis Association (Deutscher Tennis Bund) it stated as fact that all things being equal a ball will move more from left to right than from ...
4
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5answers
4k views

If the earth has gravity, why don't we all collapse to the center?

I'm sorry if the answer is obvious for you guys, but why don't we all (including buildings, road, people, the ground) collapse to the center of the earth because of gravity? Is it because we have ...
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1answer
83 views

Explain the terminal velocity equation [closed]

As explained by Method 1 on WikiHow, the equation for Terminal Velocity is: $$ V_T = \sqrt{2 \times m \times g \over ρ \times A \times C} $$ Some parts of this equation are self explanatory, and ...
7
votes
3answers
1k views

Rocky Planet in the center of System [duplicate]

We all know that mostly stars are at the center of planetary systems, but is it possible that instead of a star there was a rocky planet in the center with stars (and other planets and moons) orbiting ...
3
votes
1answer
72 views

Why does matter gather as discs around massive objects? [duplicate]

Why do discs, like rings of Saturn and the spiral shape of our galaxy form around massive objects, instead of just a (spherical?) cloud of matter?
16
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4answers
6k views

A force opposing Gravity

Every Action Has An Equal and Opposite Reaction (Newton's Third Law.) If this is the case, does gravity have an equal-opposing force? From asking around I still haven't got a very clear answer; ...
0
votes
1answer
106 views

What is $g$ when traveling quickly around a planet?

I am trying to model a rocket orbiting a planet. I want to simplify the problem so that the rocket is travelling along an infinitely long flat surface with a $g$ along the $y$-axis. This is what ...
3
votes
1answer
262 views

What is the critical mass of a planet to have an atmosphere like Earth's? [closed]

Small planets/orbits like Moon cannot have atmosphere because of their masses. They don't have enough gravity to hold an atmosphere. Then what is the critical mass that makes enough gravity to keep an ...
5
votes
5answers
13k views

Why do two bodies of different masses fall at the same rate (in the absence of air resistance)?

I'm far from being a physics expert and figured this would be a good place to ask a beginner question that has been confusing me for some time. According to Galileo, two bodies of different masses, ...
2
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3answers
694 views

While finding escape velocity, does human mass counts as the mass of Earth?

Escape velocity depends upon the mass of earth. my doubt is whether human mass adds into it or not? If it add then Earth's escape velocity would be increasing!