All Questions
14
questions
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43
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Why is time taken to go around the Sun to cover a small fixed angle proportional to the square of the distance?
I am reading Feynman's lost lecture. At this point, he asks us to consider points J, K, L and M which subtend equal angles at the sun S. And then he claims that triangles JKS and KLS are similar ...
- 430
0
votes
1
answer
66
views
Can someone help me with differential equation please? [duplicate]
here is the topic of the problem:
You are given $2$ baseballs (consider them as perfect solid spheres) have equal properties with mass $m = 0,142kg$, radius $r_0 = 0.037m$ in the space and thay are $...
- 1
2
votes
1
answer
1k
views
Why is the gravitational potential of a uniform disc not symmetric about its center?
Consider a uniform, infinitely thin disc of surface mass density $\sigma$ and radius $R$ placed in the $xy$-plane with its center as the origin.
The gravitational potential at a point on the axis of ...
- 113
1
vote
1
answer
256
views
Tidal forces mathematics
Let's calculate the difference in force, $\Delta F$, experienced by
the rocks. Because $\Delta r$ is very small compared to $r$,
$$\Delta F = F_{\text{out}} - F_{\text{in}} \approx\frac{dF}{dr}\Delta ...
1
vote
1
answer
129
views
Finding velocity $v$ and position $r$, given a time $t$ under the acceleration of a gravitational force [closed]
I was messing with the maths, when I tried to find the velocity as a function of time, $v(t)$, and the position, also, as a function of time, $r(t)$ under the gravity force.
$$ m \ddot{r} = -G \frac{...
- 1,515
0
votes
1
answer
166
views
Maximum height of a projectile when $g$ is not constant [closed]
How can I calculate the maximum height of a projectile that is launched from the surface of the earth with a given initial velocity? (ignoring air resistance in the atmosphere)
I understand how to ...
1
vote
2
answers
73
views
How do you differentiate this differential equation? [closed]
I have to differentiate this equation (Gravitational force between N-Bodies)
$\begin{align}
\frac{d^2}{dt^2}\vec{r_i}(t)=G
\sum_{k=1}^{n}
\frac
{m_k(\vec{r}_k(t)-\vec{r}_i(t))}
{\lvert\...
0
votes
3
answers
147
views
The force of gravity between a shperical shell and a particle
I am trying to understand the proof of why the force acting on a spherical shell and a particle is
$$\frac{GMm}{r^2}$$
Where M is the mass of the sphere and m is the mass of the particle.
I am looking ...
- 5
0
votes
4
answers
990
views
Acceleration due to gravity during its journey up and down
When we throw an object up into the air, ignoring air resistance, etc, we define acceleration to be -9.8 m/s^2. When it goes down after its journey up, like a parabola, do we define the acceleration ...
- 23
-1
votes
1
answer
4k
views
Calculating the distance between two masses with respect to gravitational force [duplicate]
Call them $m_1,m_2$. They are compressed to their center of masses, if you wish. If the initial distance at $t=0$ is $d$, is there a formula or an efficient way to calculate the distance between them ...
- 121
1
vote
3
answers
121
views
Bounds of Integration (with respect to something that is not time)
I have been reading Richard Feynman's lectures and came across an interesting proof regarding the Earth's gravitational force. At one point in the proof, Feynman uses the following the integral:
$\...
- 954
0
votes
2
answers
182
views
How can we treat dV like this?
Now, to calculate the gravitational potential due to a ring(or any object for that matter) at a distance $r$ we consider a tiny mass $dm$ on the ring, and calculate the potential $dV$ due to this ...
- 1,096
2
votes
1
answer
81
views
Satellite and gravitational acceleration
According to $0.5gt^2$ object will fall 5m in first second.
Earth curve is 5m for 8km
So if we can project object at 8000 m/s speed object will never fall into ground.
Above scenario is correct for ...
- 29
1
vote
1
answer
124
views
How to model terminal velocity as a function of gravitational acceleration?
Taking the most simplistic form of terminal velocity, $v=\sqrt{\frac{mg}{c}}$
I want to try and derive an equation that models the velocity as g changes in height.. Because obviously the terminal ...
- 546