# Tag Info

1 vote

### Why does gravity cause objects to pull other objects with constant acceleration and not constant force?

Every single atom pulls every other atom with the same force (not exactly but good enough). If you double the weight of one body and triple the weight of the other, then you have twice as many atoms ...

### Why does gravity cause objects to pull other objects with constant acceleration and not constant force?

Imagine that you have an object of mass $M$ attracted to the earth, with the force acting on the object being $F$. You are asking if we can prove intuitively why $F$ should be proportional to $M$ - i....

### Why does gravity cause objects to pull other objects with constant acceleration and not constant force?

Why does gravity cause objects to pull other objects with constant acceleration and not constant force ? Science generally doesn't give very satisfactory answer to "why is the universe the way ...

### Why does gravity cause objects to pull other objects with constant acceleration and not constant force?

In general objects don't experience a constant acceleration due to gravity. But near the surface of the Earth they nearly do. The gravitational force acting on a pair of objects depends on their ...

### Why does gravity cause objects to pull other objects with constant acceleration and not constant force?

I think gravity may not be a force per se. If it were a force then it could be expressed as a quanta. Unfortunately, Einstein's theories cannot be reconciled with quantum theory and quantum theory is ...
Accepted

### Sign of force for assumed $mgy$ gravity

If you assume force is $mgy$: After reading OP's comments, it seems that OP just wants to understand how to solve a problem where the force is proportional to the displacement. The main problem the ...

### How do i calculate a projectile range accounting for a planet's curvature?

I tried to figure this too. I had this hypothesis: if rocket is launched to some angle instead of straight up, Apoapsis should be more high because planet has curvature. I tried to calculate how high ...

### Time taken for object in space to fall to earth

I think that the equation $T=\frac{\pi}{2} * \sqrt(\frac{R^3}{2Gm})$ is incorrect equation. If we tested the equation with a height of $h=100m$ away from the surface of earth. It could be good to use ...

### Escape velocity work done problem

to provide velocity to send to infinite distance from gravitational pull of earth so for that we have to apply external force This is called an “initial velocity”. The problem begins at the “initial ...

### Can mass be negative?

We don't have any physical evidence for negative masses. In general relativity there are some interesting mathematical solutions, such as "wormholes," that become stable if you have access ...
Accepted

### What is the smallest known gravitationally bound system?

Some asteroids or comets are not solid bodies. Instead they are collections of rubble, weakly held together by gravity. The smallest such body is probably the system you are thinking of. JPL's Small-...

### How much kinetic energy would a star in a galaxy have if it fell to the center?

A fair answer can be achieved using Newtonian physics. Assuming that the star was stationary prior to infall (as you want), we would need to find its potential energy. If it falls to the center, then ...

### Why do gravity and electricity sometimes obey inverse square laws over the same distance scale?

The modern point of view is that we should understand field theories as effective field theories, or low energy approximations of more complete theories. Because of the uncertainty principle, "...

### Why do gravity and electricity sometimes obey inverse square laws over the same distance scale?

To get an idea as to why it helps to think about field lines. If you imagine a sphere enclosing an electric charge or mass then the number of field lines coming into or out of the sphere depends only ...
Accepted

### Find the acceleration of a block sliding down on an accelerating inclined place

The acceleration $\mathbf a$ is referred in the frame of the inclined plane. \begin{align} \mathbf b &= b\cos \theta \, \mathbf i+b\sin \theta \, \mathbf j \\ \mathbf g &= g\sin \theta \, \...

### Is there a way to express the collisionless boltzmann equation in terms of positions, velocities, times, without the distribution function?

I think what you're looking for is called Newton's second law. You know the force acting on a single particle, you calculate its acceleration, and you follow this particle in its motion through space ...
1 vote

### Is there a way to express the collisionless boltzmann equation in terms of positions, velocities, times, without the distribution function?

A single particle will just follow Newton's force equation, using the acceleration as $a=F/m$, where $F$ is the prescribed force on particles. The Boltzmann equation is built from the assumption that ...

### How much kinetic energy would a star in a galaxy have if it fell to the center?

The rotation curve $v ( r )$ for the galaxy will give the centripetal force experienced at any radial position $F = \frac{mv^2}{r}$. The kinetic energy in this scenario would be \$ \frac{mV^2}{2} = KE =...