# Questions tagged [free-fall]

Free fall is any motion of a body where gravity is the only force acting upon it. In general relativity, where gravitation is reduced to a space-time curvature, a body in free fall has no force acting on it.

526 questions
Filter by
Sorted by
Tagged with
68 views

### Do objects really "fall" at the same rate? [duplicate]

I understand that a hammer and a feather were dropped on the moon and they both landed at the same time. I understand that for all practical intents and purposes all objects do fall at the same rate. ...
• 129
26 views

### Can two objects of different mass experience the same air resistance? [duplicate]

This question is assuming that the objects have the same shape and size, but different masses. I know that all objects have the same gravitational acceleration on earth, which is about 9.8 m/s^2. ...
• 539
82 views

### How could I calculate the time it will take for light and mass to go towards a black hole and come back, to and from constant radial distances?

If you have a "perfect mirror" and a "perfect trampoline" at some constant distance outside a black hole's event horizon: a) How would a shell observer at some distance farther ...
• 171
115 views

### Equation for the curve of a free falling particle in Kruskal diagram

I'm currently trying to help a friend who is taking a GR course (she is an experimentalist, and I'm rusty as hell, please be patient). We got stuck in an issue concerning Kruskal coordinates. We are ...
1 vote
27 views

### Gravitational attraction between two bodies and gravitational accelaration [duplicate]

Since Newtons laws on gravity state that the gravitational attraction between two bodies is directly proportional to their masses and inversely proportional to the square of the distance between them, ...
• 123
1 vote
108 views

### Necessity of equivalence principle

Is the equivalence principle necessary to formulate general relativity or is it possible to formulate general relativity without it?
• 31
208 views

### Definition of free fall in GR

I apologize if this question is very elementary. Somewhere I've found the following: Freely falling observers (resp. photon) move on timelike (resp. null) geodesics. Please note that by definition, ...
• 133
38 views

### Question regarding projecticle in freefall disregarding air resistance [closed]

This question is regarding the following problem A stone is thrown up from the top of a tower 20 m with a velocity of 24 m/s at an elevation of $30^\circ$ above the horizontal. Find the horizontal ...
• 173
208 views

### Why will a cylinder tend to freefall on its side?

In a video I saw about the U.S. military’s idea “Rods from God”, it said a uniform steel cylinder will tend to freefall in the air on its side if not corrected. It won't freefall vertically if left to ...
• 275
73 views

### Why do objects with more mass fall at a faster rate (factoring in air resistance)? [duplicate]

My class had to do an online simulation about the different free fall times of objects, both on Earth and in a vacuum. In it, I noticed that in an atmosphere, objects with greater mass fell faster ...
• 539
10 views

### Couple on free falling rod [duplicate]

When free falling rod is punched at top then it would start rotating as shown below : But only force here is punch force so how does a couple form here? Gravity is present but isn't it along the axis....
17 views

### Time taken for an object to fall [duplicate]

Time taken for an object to fall is generally given by $$t=\sqrt{\frac{2h}{g}}.$$ But this is only true under the assumption that gravitational acceleration is constant. With variable gravity what ...
72 views

### When doing Ice Skating, is it more painful to fall in motion or without motion?

Let's imagine I'm ice skating on a perfectly flat surface. In the first scenario, I am falling motionless. I expect my forces to looks like this: In the second scenario, I am falling with some speed, ...
78 views

### Dropping a skyscraper (hypothetical question)

This is hypothetical question: imagine a tall skyscraper says 1000m tall is lifted by a nign indestructible cables attached only at the top of the building. When the cable is released what happens? ...
• 13k
41 views

### Does it takes more or less effort to dribble in a micro-$g$ environment?

Imagine an astronaut is practicing with a standard official basketball on an orbiting space station. Assume everything is in free fall so I wonder would it consume less or more effort to dribble ...
• 13k
61 views

### What would happen if I swirl a bottle of water in the space station?

Right now I am swinging a bottle of water in a tight circular motion to form a vortex, the vortex will last quite a while after I stopped swinging it. The vortex will took the shape of a funnel in 1g ...
• 13k
1 vote
57 views

### Throwing a pencil up in an elevator speeding upward

The classic question is "What happens to a pencil if I, standing in an elevator speeding downward, lets go of it at the exact second the elevator begins its fall?" As I understand, the ...
• 1,090
291 views

• 282
435 views

### What is the weight of a body during free fall?

Is it '0' or is it equal to the product of the mass of the body and acceleration due to gravity? Please explain in relation to weightlessness of body in freefall.
255 views

### Could you feel your weight falling through the a tube drilled through the center of the earth?

Suppose you drill a hole through the center of the earth (assume the earth is uniform and no air resistance) and you jump in. Would you be "weightless" throughout the entire fall? The reason ...
• 396
800 views

### How are objects kept free falling in the LISA experiment?

I'm watching a video about the LISA experiment, which will be used to detect gravitational waves. In there, three space stations will be launched and will follow the Earth in its revolution around the ...
162 views

### Are all objects freefalling at the same rate inside a black hole?

We know the phrase "all objects move at the same rate when freefalling regardless of their mass" (interestingly this isn't even true because the objects are exerting their own gravity, but ...
77 views

### "Outrunning pressure": Liquid in free-fall

I've checked out related questions and didn't see an answer to my question. Scenario: Liquid in open-top container, together accelerating downward with magnitude $g$. It was straightforward for me to ...
• 1,216