All Questions
Tagged with newtonian-gravity conventions
93
questions
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298
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What is the height in the potential energy formulation? [duplicate]
Most examples I've seen describe the (gravitational) potential energy e.g. with an example of a ball thrown upwards, and explain how the sum of the ball's kinetic and potential energy is constant at ...
- 13
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4
answers
2k
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Why is gravity considered a negative vector in a pendulum question?
In many places and tutorials, gravity is often considered as a negative vector.
I am confused as to why is that? I though I was missing something from trigonometry but it was just negative in first ...
- 171
1
vote
1
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97
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Gravitational potential energy sign
Following is a small derivation just so I can explain my question. The gravitational potential energy is:
$$(*)U_g = -\frac{GMm}{r}$$
And:
$$ \Delta U =-GMm(\frac{1}{r_{final}} - \frac{1}{r_{initial}})...
- 1,038
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1
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341
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How can we choose any level for gravitational potential energy to be zero?
In my book, I read that we can choose any level as Zero Gravitational P.E. and measure height of objects above it and call its energy 'mgh'. But by saying that all the points on that level is of zero ...
- 5
6
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Why is the constant in Coulomb's law written in terms of $\pi$ but not the constant in Gravitation?
What is the significance of writing it as $\frac{1}{4\pi \epsilon _0}$? Why not just name the whole thing $\epsilon _0$? And if there is a significance, why not do the same thing for gravitation?
I ...
- 6,355
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1
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Reference Point and Change in Potential Energy
Okay so I am VERY confused. Everything online is telling me that I can choose any reference point for potential being zero and still get a consistent result for potential difference HOWEVER I have ...
- 43
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54
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Can we make uniformity in marking zero potential? Say it at earths surface or at infinity from earths surface?
The gravitational potential energy at infinity os supposed to be zero. Since body always moves towards lower potential, the gravitational potential is taken as negative so that gravitational potential ...
- 111
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166
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Why isn't the work done by gravity positive in this situation?
I want to find the work done by the force of gravity to move an object of mass $m$ from infinity to a point $P$ at distance $r_p$ from a body of mass $M$ (that I assume fixed). The formula should be
\...
- 113
3
votes
3
answers
125
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What is wrong with this calculation of work done by an agent bringing a unit mass from infinity into a gravitational field? [duplicate]
Let us assume that a gravitational field is created by a mass $M$. An agent is bringing a unit mass from $\infty$ to distance $r < \infty$, both measured from mass $M$.
The agent is always forcing ...
- 49
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3
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988
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Why is the gravitational potential energy defined as negative? [duplicate]
It is said that since work is done by the gravitational potential itself , so at a finite distance the gravitational potential energy of the body is negative.
Could someone explain why?
0
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4
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If Gravitational potential energy increase with height then why it is 0 at infinity?
Due to MGH relation, if we increase height then potential energy increases. Then why it is zero at infinity?
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119
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Sign Problem When Dealing With Quadratic Air Resistance and Gravity [closed]
While dealing with an object falling vertically, and subject to quadratic air resistance, an equation of motion that is often presented is
\begin{equation*}
m\dot{v} =mg-cv^{2}
\end{equation*}
In ...
- 15
-1
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2
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321
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The reference point of potential energy
In one dimension (I am not familiar with multivariable calculus), potential energy is defined as
$$E_p = -\int F \ dx$$
This is an indefinite integral, and the integration constant $C$ is involved ...
- 485
0
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5
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1k
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What is the reason for work done by gravitational force being negative?
When a body is moved from $r=∞$ to say, $r=R$, work done by the gravitational force is $-(GMm)/R$.
Why is it negative even though the Force and the displacement of the body is in the same direction. ...
- 72
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3
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352
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Sign of gravitational acceleration
The gravitational potential energy comes from the formula $mgh$ where $g$ is always $>0$.
But when we get to choose it's sign? I figured out, it really depends on what you choose as positive axis ...
- 101