Questions tagged [newtonian-gravity]
This tag is for questions regarding the Newtonian model of gravity in which the force between two objects is given by $~GMm/r^2~.$ It is a natural phenomenon by which all things with mass or energy – including planets, stars, galaxies, and even light – attract one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides.
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Is gravitational potential energy of body by $mgh$ negative? [closed]
Consider a 15kg object at 1m from earth ground level,
is P.E = 15kg * 9.8m/s^2 * 1m = 147J
or P.E = -Gm1m2/r^2 * h = -9.8 * 15kg * 1m= -147J
after browsing for a while on debate of potential energy's ...
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How do you derive the compound pendulum formula?
How do you derive $$T=2\pi\sqrt{I/mgl},$$ where $I$ is the moment of inertia and $l$ is the length of the pendulum?
Is it even the right formula? How would I derive a compound pendulum formula for a ...
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Why is potential energy negative when orbiting in a gravitational field?
I had to do a problem, and part of it was to find the mechanical energy of satellite orbiting around mars, and I had all of the information I needed. I thought the total mechanical energy would be the ...
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Does an object falling from very large height as compared to radius of Earth rotate as well due to gravity?
If let us say a rigid body is falling from a height such that value of $g$ remains same then the body does not rotate at all about the centre of mass as centre of mass and gravity coincide hence net ...
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How accurate does the ISS's velocity and altitude need to be to maintain orbit?
We know the the ISS is not drifting weightless in space, but rather is constantly falling as it circles the Earth. To do this it must be at a specific altitude and moving with a specific velocity. ...
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What would happen to the moon's orbit if we reduce (instantaneously) its mass? [closed]
In my opinion the moon's orbit shouldn't change, because an orbiting body is a free falling object and the trajectory of a free falling object is not affected by its mass (because the inertial mass ...
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Interpretation of gravitational potential in 2+1D
From Gauss's law of gravity reduced to 2+1 dimensions, one can easily show that the gravitational force follows an inverse law, i.e.
$$
\mathbf{F}(\mathbf{r}) =- \frac{G m M}{|\mathbf{r}|}\hat{\mathbf{...
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Does Earnshaw's theorem apply to electrostatic + gravitational systems?
I've been learning about particle traps and Earnshaw's theorem. When dealing purely with electrostatic forces the theorem makes intuitive sense to me. But does it really apply to systems involving ...
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When an object is thrown towards the sky it starts to gain potential energy, why?
I didn't think so because when an object is thrown towards the sky it already has kinetic energy and it looses it's energy due to the gravitational force of the earth.
When the object looses all of it'...
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Doubt on conservation of angular momentum for Kepler's laws
Just before proving Kepler's laws, my Professor claimed that if $\vec{F}$ is a central force with center $O$ and it is the only force acting on a point $P$, then the trajectory of $P$ is a curve plane....
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Why are fields described as force divided by mass or charge?
I have read that application of force on a body from a distance, like gravitational or electrostatic force is a two-step process, first, the field is created by the body, then, the application of ...
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Local vs distant gravity effects where is the boundary line of effective control? [closed]
I'm not one of the 'gravity is only a theory' crowd or a flat earther that thinks gravity is fake and that down is always down. but thinking about gravity and what has been put forward by many great ...
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Has our knowledge of astrophysics and gravity reached the point where we can accurately calculate Lagrange points?
is it possible for us today given the knowledge we possess of gravity and our success with inserting satellites in to steady/ geosynchronous orbit and any knowledge we have on the relative size (and ...
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Error concerning projectile motion in respected textbook?
In the textbook Fundamentals of Physics by R. Shankar of Yale Open Courses, appears the following assertion pertaining to a car driving off a cliff, which seems correct:
This is exactly how long it ...
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From my reference frame, why does the Earth need a huge kinetic energy [$0.5M_E(11200)^2=3.75*10^{32}$ joules] to escape me? [closed]
I wake up screaming into the void, when I see the Earth almost touching me but going away from me at 11.2 $km/s$.
I don't remember what happened before I woke up. I faintly recollect being cannoned up ...
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