The Newtonian model of gravity in which the force between two objects is given by GMm/r^2.
1
vote
1answer
446 views
Friction due to air drag at high speeds
I am trying to set up this problem, but I am not sure how to go about doing so. (From University Physics, Young & Freedman):
You throw a baseball straight up. The drag force is proportional to
...
2
votes
1answer
81 views
Mutual Interaction of $N$-Particles in a Cartesian Plane
I am making a simulation of $N$-Particles in a cartesian plane and need help with understanding the basics.
At anytime, in my particle system, I will have $N$ number of particles. I am treating the ...
2
votes
1answer
262 views
Radial fall in a Newtonian gravitational field [duplicate]
Suppose an object of mass $m$ starts at rest at a radial distance $ r_0$ from a perfectly spherical mass $M$ (where $m << M$), $r_0 > R =$ radius of $M$.
Can we analytically determine when ...
2
votes
3answers
833 views
What is terminal velocity?
What is terminal velocity? I've heard the term especially when the Discovery Channel is covering something about sky diving. Also, it is commonly known that HALO (Hi-Altitude, Lo-Opening) infantry ...
3
votes
1answer
83 views
What is the maximum mass of planet HD 40307 g
Recently discovered planet HD 40307g around HD40307 Star system is claiming that its inside a habitual zone of a solar system. Besides It has water where life could be evolved.
I tried to calculate ...
0
votes
1answer
80 views
What is the orbital motion where both foci are located at one point?
What is the orbital motion where both foci are located at one point? I know that an ellipse orbit is motion with two distinct foci.
6
votes
3answers
199 views
The feasibility of a satellite orbiting at a fixed time
I was speaking with some friends of mine, one of whom was an aerospace engineer. He posited the infeasibility of a hypothetical "Margaritaville Satellite" that orbited earth in such a way that ...
1
vote
1answer
170 views
Result of increasing the radius of earth?
How can increasing the radius of earth may cause an impact on the solar system ? Like, would earth may start making a bigger orbit (due to increase in size and wait) or vice versa ? or else ?
PS: The ...
4
votes
5answers
2k 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 ...
3
votes
1answer
211 views
How long will it take for a bullet to reach a Geostationary orbit?
I'm curious to know this. Neglect air friction and imagine a bullet that were shot normal to the Earth's surface, from the Equator. I will have to consider the Coriolis effect and so I expect the path ...
1
vote
1answer
125 views
How much runway does the space shuttle need to land?
A textbook question proposes the following scenario:
NASA needs to plan emergency landing sites for the Space Shuttle (RIP). There are a number of things to consider. The shuttle touches down no ...
12
votes
1answer
468 views
James Webb Space Telescope's halo orbit at Lagrange point L2
The James Webb Space Telescope (JWST) is expected to be launched in 2018 and operate in the L2 vicinity, about 1.5 million km from Earth.
It will be placed in a halo orbit around the unstable L2 ...
3
votes
1answer
258 views
About Newton's Shell Theorem
Newton proved in Principia that the total gravity that a sphere exerts over a material point is the same as if all the mass of the sphere were concentrated on its center.
I wonder if it's possible to ...
0
votes
1answer
101 views
Non-relativistic Kepler orbits
Consider the Newtonian gravitational potential at a distance of Sun:
$$\varphi \left ( r \right )~=~-\frac{GM}{r}.$$
I write the classical Lagrangian in spherical coordinates for a planet with mass ...
6
votes
2answers
150 views
Is it possible to use a balloon to float so high in the atmosphere that you can be gravitationally pulled towards a satellite?
A recent joke on the comedy panel show 8 out of 10 cats prompted this question. I'm pretty sure the answer's no, but hopefully someone can surprise me.
If you put a person in a balloon, such that ...
0
votes
2answers
238 views
How Newton found Gravitational acceleration?
How Newton found Gravitational acceleration (g) of The Earth?
Can you describe the methods to find and prove it(g value)?
(may be describe both classical methods and modern methods)
2
votes
2answers
170 views
Parabolic motion and air drag
Are this equations correct, in order to calculate the parabolic motion of an arrow with the computation of the drag with the air?
$$
\begin{cases}
x(t)=\left(v_0-\frac{1/2C_DA\rho ...
3
votes
1answer
228 views
Finding the diameter a parachute must be to land a probe on Mars at specific speed
Hi I'm trying to solve this textbook example but I don't know where to begin;
NASA has decided to send an experimental probe to Mars. Its weight on earth is $40 kg_f$. When the probe is near ...
1
vote
2answers
118 views
Kinetic Energy of Stone
If a stone is launched upward, of which is subject to gravity and air resistance, which of the following will have a greater kinetic energy? The stone at a point on its way up, or the stone at the ...
2
votes
0answers
87 views
What is the correct way of integrating in astronomy simulations? [closed]
I'm creating a simple astronomy simulator that should use Newtonian physics to simulate movement of plants in a system (or any objects, for that matter). All the bodies are circles in an Euclidean ...
1
vote
3answers
621 views
Newtonian Bending of Light?
I ran across THIS Newtonian explanation for the bending of light. Does it have any merit?
0
votes
1answer
108 views
What is the gravity at the center of the Earth? [duplicate]
Possible Duplicate:
Would you be weightless at the center of the Earth?
Supposing there is a cavity at the center of the Earth, what is the gravity there? What will be its direction and ...
2
votes
3answers
176 views
Weightlessness by a parabolic flight
Do you actually achieve weightlessness during a parabolic flight? Because I believe I heard somewhere did you achieve 'near-weightlessness' and not 'weightlessness' (if this is true, why is this?) ...
4
votes
4answers
418 views
what is the 2D gravity potential?
In 3D, I can calculate the total force due to gravity acting on a point on the surface of the unit sphere of constant density, where I choose units so that all physical constants (as well as the ...
3
votes
3answers
417 views
Free falling objects
My teacher and I are in the middle of an argument because she says that if you were to drop two objects at the same time and the same height, but with different initial velocities, both of them would ...
5
votes
3answers
230 views
Differences between the gravitational constants $G$ and $g$?
There's a formula (described by Sir Isaac Newton) that gives the force acting between two objects:
$$F = \frac{Gm_1m_2}{r^2}$$
And then there's a formula for weight of an object
$$w = mg$$
My ...
0
votes
1answer
342 views
Satellite Orbital Period [closed]
I know I can calculate the period of a satellite orbit by Kepler's third law, but somehow it does not work out.
The sattelite is 20200km from surface of the earth.
$r=$orbits radius=earths ...
1
vote
2answers
99 views
A particle of charge $-e$ orbits a particle of charge $Ze$, what is its orbital frequency?
A point particle $P$ of charge $Ze$ is fixed at the origin in 3-dimensions, while a point particle $E$ of mass $m$ and charge $-e$ moves in the electric field of $P$.
I have the Newtonian equation of ...
1
vote
1answer
224 views
Einstein's Explanation for gravity vs. Newtonian
I was trying to understand the Einstein's explanation for gravity (gravitational force), and while I am able to understand why two moving masses will be attracted, due to the curving of the space, I ...
0
votes
0answers
21 views
Helpful tutorials on force [duplicate]
Possible Duplicate:
List of good classical physics books
I'm having a hard time understanding force in my highschool AP physics class, i looked through youtube but without luck. Could ...
0
votes
1answer
156 views
How can the Air friction force be applied to an object?
Suppose we have an object and we throw it straight upward in the air. How do we apply the Air friction force to this object while moving upwards and after that downwards? Sorry if it's easy because ...
3
votes
1answer
363 views
What would it be like if we had a planet very close to us?
My desktop background rotates through a bunch of space and nature scenes, and this one came up.
What would be the effect on people walking around down here, if another earth was looming overhead ...
0
votes
0answers
21 views
What will be my motion inside earth [duplicate]
Possible Duplicate:
If it was possible to dig a hole that went from one side of the earth to the other
Suppose I drill a hole in earth through the centre and out from the other side. If I ...
2
votes
1answer
51 views
Single plane Ring system [duplicate]
Possible Duplicate:
Why are our planets in the solar system all on the same disc/plane/layer?
I've noticed this in many pictures, Planets are shown with a single ring around them (in some ...
3
votes
2answers
216 views
At what g is terminal velocity not terminal?
How weak would gravity need to be in order for a human to reliably survive the terminal velocity of falling through air?
(Context: watching scifi on a space station with a variety of artificial ...
1
vote
2answers
416 views
Free fall of two spheres made of same materials, different masses, with air resistance
Two people falling with the same parachute will gain different speeds if their masses are different. The upward air drag will needed to be bigger for a heavier person, since gravitational force is ...
0
votes
0answers
78 views
Mathematical Formulation of the laws of classical physics
By classical here I mean non-quantum mechanical, and everything that is developed afterwards such as color, etc.
I am wondering if we can look at our Universe mathematically like this:
Let ...
0
votes
1answer
66 views
What is the pause called at the apex of an object's trajectory?
My apologies for such a basic question--I am a musician, not a physicist. But I cannot anywhere find the word, if one exists, that describes that elegant pause of an object such as a ball, thrown ...
0
votes
1answer
82 views
Newton's Gravitational Law [closed]
Is this correct..?
Gravitational constant, $G = 6.67 × 10^{-11} Nm^2kg^{-2}$
Mass of Sun, $M = 1.99 × 10^{30} kg$
Mass of Earth, $m= 6.02 × 10^{24}kg$
Distance between Sun and Earth, $R= 1.5 × ...
2
votes
2answers
146 views
Is the gravitational constant G a minimum value in some sense?
Assume a central body of mass $M$, and call $a$ the acceleration of a test
body at a distance $r$ due to any interaction whatsoever with the central
body. Is is correct to say that the ratio $a r^2/ ...
2
votes
2answers
112 views
Force to use in harmonic oscillation through the inside of a planet
I am to find an equation for the time it takes when one falls through a planet to the other side and returns to the starting point. I have seven different sets of values - mass of object falling, mass ...
0
votes
0answers
19 views
Capsule traveling through a planet, find time for return [duplicate]
Possible Duplicate:
If it was possible to dig a hole that went from one side of the earth to the other
A corporation is building attractions in outer space, in which they drill tunnels ...
0
votes
2answers
2k views
Why do objects with different masses fall at the same rate? [duplicate]
Possible Duplicate:
Confused about the role of mass
Today we were in our Literature class talking about the Renaissance and the Enlightement and our teacher also said that scientific ...
0
votes
2answers
99 views
Calculating kinetic energy?
Would this be a valid equation to calculate kinetic energy created from a drop from a height:
$$E_{kinetic} ~=~ v_{vertical}tmg$$
Velocity multiplied by time gives distance. Distance multiplied by ...
3
votes
1answer
605 views
Is acceleration due to gravity constant?
I was taught in school that acceleration due to gravity is constant. But recently, when I checked Physics textbook, I noted that
$$F = \dfrac{G \cdot m_1 \cdot m_2}{r^2} $$
So, as the body falls ...
33
votes
7answers
3k views
Why is the Earth so fat?
I made a naive calculation of the height of Earth's equatorial bulge and found that it should be about 10km. The true height is about 20km. My question is: why is there this discrepancy?
The ...
3
votes
2answers
159 views
Gravitational inverse-square law
I was looking at the gravitational inverse-square law:
$$
F_G = G \frac{Mm}{r^2}
$$
This law comes from some experimental data? Why it is an exact inverse-square law? Could it be
$$
F_G = G ...
5
votes
2answers
199 views
Why is there this asymmetry between the two foci of an orbital ellipse?
Why does the Earth revolve with the Sun at one of its foci? Does the other focus do nothing? Why is there this asymmetry in our solar system?
1
vote
2answers
213 views
The two-body problem: What is force between them?
Two bodies with similar/different mass orbiting around a common barycenter.
What is force between them, where $F_{12}$ is the force on mass 1 due to its interactions with mass 2 and $F_{21}$ is the ...
0
votes
1answer
125 views
Vertical Loop like Anti-gravity
Let's take a bottle (no cap) with half its volume filled with water. If we rotate the bottle at some slower average velocity, water does not drop out of it. The same principle works on Roller ...
