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78
votes
8answers
16k views

Don't heavier objects actually fall faster because they exert their own gravity?

The common understanding is that, setting air resistance aside, all objects dropped to Earth fall at the same rate. This is often demonstrated through the thought experiment of cutting a large object ...
33
votes
6answers
36k views

Could someone jump from the international space station and live?

Felix Baumgartner just completed his breathtaking free-fall skydiving jump from $120,000\,\text{feet} = 39\,\text{km}$ above the Earth, breaking the speed of sound during the process. I was wondering ...
29
votes
6answers
1k views

Can I survive a free fall using a ramp and a rope?

Can I survive a free fall by carrying a very light and resistant ramp using a rope? Note: lets assume the ramp is a little bit heavier at the bottom and I am very skilled at making it always land ...
26
votes
5answers
4k views

Which ball touches the ground first?

This is a very well known problem, but I can't find an answer in the specific case I'm looking for. Let's consider two balls : Ball 1 weighs 10 kg Ball 2 weighs 1 kg Balls have identical volumes ...
15
votes
6answers
703 views

Does the weight of an hourglass change when sands are falling inside?

An hourglass H weighs h. When it's placed on a scale with all the sand rested in the lower portion, the scale reads weight x where x = h. Now, if you turn the hourglass upside down to let the sand ...
12
votes
7answers
4k views

Would it help if you jump inside a free falling elevator?

Imagine you're trapped inside a free falling elevator. Would you decrease your impact impulse by jumping during the fall? When?
12
votes
1answer
2k views

From how high could have Felix Baumgartner jumped without disintegrating like a shooting star?

Today Felix Baumgartner jumped from 39 kilometres high and reached the earth safely. Just considering friction, from how high can a human jump? I expect that from a certain height, he would have ...
11
votes
5answers
27k views

jumping into water

Two questions: Assuming you dive head first or fall straight with your legs first, what is the maximal height you can jump into water from and not get hurt? In other words, an H meter fall into ...
8
votes
4answers
2k views

Water pressure in free fall

The increasing water pressure as you go deeper is generally explained in terms of the weight of the water column above the observation point pressing down. The question, then, is what would happen if ...
7
votes
2answers
405 views

Equivalence principle and radiation from falling particle

I am currently having a hard time solving a problem of GR from Lasenby's book. I can't make it more clear than by quoting the exercise: 7.2 A charged object held stationary in a laboratory on the ...
5
votes
5answers
3k views

Why do two bodies of different masses fall at the same rate (in the absence of air resistance)?

I'm far from being a physics expert and figured this would be a good place to ask a beginner question that has been confusing me for some time. According to Galileo, two bodies of different masses, ...
5
votes
1answer
578 views

Did Galileo offer an explanation why his law of falling bodies is independent of mass?

Naively, (and endorsed by Aristotle) one expects heavier things to fall more quickly, Galileo Galilei showed in fact this is not correct, and that in fact how they fell as independent of mass (if air ...
4
votes
2answers
419 views

Consequences of destroying a space elevator

Suppose there is a fully functional space elevator built on Earth. The base is attached to coordinates $ (\lambda, \varphi) = (0,0) $ e.g., on the equator on the zero-meridian. What would happen ...
4
votes
1answer
542 views

Radial fall in a Newtonian gravitational field [duplicate]

Suppose an object of mass $m$ starts at rest at a radial distance $ r_0$ from a perfectly spherical mass $M$ (where $m << M$), $r_0 > R =$ radius of $M$. Can we analytically determine when ...
3
votes
3answers
874 views

Free falling objects

My teacher and I are in the middle of an argument because she says that if you were to drop two objects at the same time and the same height, but with different initial velocities, both of them would ...
3
votes
4answers
2k views

Can a balloon float into space? (+orbital velocity)

After watching the recent "space jump" a question arose. Why can a balloon not float into space? Can one be made/designed to do this? Next, everything in orbit is falling back to earth. It only ...
3
votes
2answers
174 views

Were there any efforts made by early physicists to discover and explain how composite bodies fall?

At the dawn of the modern era, Galileo discovered and described how composite bodies fall through the air (or at least the discovery is usually attributed to him). I'm interested in whether this had ...
3
votes
2answers
365 views

Is the speed of a person falling down different if doing a forward somersault during the fall?

Let's imagine this in an situation where a person jumps down from a smaller building, a garage for example. The exact numbers aren't really important here, since I'm not aiming for an exact answer, ...
3
votes
4answers
127 views

Force of an impact on water

Today, at the Brazilian news, I heard that a men fell from a cruise into the sea, from a height of 50m, and decided to see if he could have survived. I took his weight for being 80kg. I did ...
3
votes
1answer
242 views

How deep is the well, given this data?

A rock is dropped into a well. A timer starts when the rock is dropped and is stopped when the noise of the rock hitting the ground of the well is heard. How deep is the well? Here's what I have so ...
3
votes
4answers
12k views

Calculating impact force for a falling object?

Good evening, I'm trying to calculate what kind of impact force a falling object would have once it hit something. This is my attempt so far: Because $x= \frac{1}{2} at^2$, $t=\sqrt{2x/a}$ $v=at$, ...
3
votes
3answers
543 views

A freefalling body problem, only partial distance and time known

Well, I've been trying to figure out a problem which I imposed on myself, so no literal values included. Unfortunately, my brain is not cooperating. The problem states: What is the height from ...
3
votes
1answer
857 views

Coriolis force in free fall

Does the coriolis force has any measurable effect in free fall from large heights? Take for example the sky diving experiment by F. Baumgartner who started from a height of about 40 km above New ...
3
votes
1answer
297 views

Wave pulse on a freely falling rope

Consider a rope hanging from the ceiling (massive / massless irrelevant, I suppose). A wave pulse is set up on the rope. Just as the wave pulse starts propagating on this rope, the top of the rope is ...
3
votes
0answers
899 views

Gravity - What happens when two objects of unequal masses fall freely towards the ground? (Revisited)

The common perception regarding what happens when two objects of equal sizes but unequal mass are allowed to fall freely towards the ground is that - both the objects make contact with the ground at ...
2
votes
4answers
8k views

Free falling of object with no air resistance

Why does an object with smaller mass hits the ground at same time compared to object with greater mass? I understand the acceleration due to gravity of earth will be same but won't the object with ...
2
votes
2answers
1k views

How do I approach this conservation of energy problem, symbolically

In the absence of nonconservative forces such as friction and air resistance, the total mechanical energy in a closed system is conserved. This is why that when I toss an object directly upwards, the ...
2
votes
2answers
185 views

Why does a flat clover-like shape fall slower when it is rotating?

The plastic flat clover-like shape pictured below falls noticeably slower when it is rotating fast. I wonder why. Its three edges are flat, so I don't think that the rotation makes it act like a ...
2
votes
4answers
185 views

Why is the time taken for something to fall proprtional to acceleration due to gravity?

This is a continuation of this question. I saw in a piece of writing (that I no longer seem to be able to aquire) on dimensional analysis that: $$t \propto h^\frac{1}{2} g^\frac{-1}{2}.$$ How can ...
2
votes
3answers
239 views

Why can't we think of free fall as upside down rocket?

/\ / \ | | | m | | | ------ <--- floor (Rocket A) This rocket is accelerated (g) upwards then mass(m) falls on the floor. ...
2
votes
6answers
889 views

Which person can handle falls from big heights better: lighter or heavier?

This probably includes a little of biology, but I believe it's mainly physics, so I hope it's ok to ask here: Imagine 2 persons: Person A weights 120 pounds and person B weights 180 pounds. Imagine ...
2
votes
1answer
72 views

Why does a LED light up in reverse direction at a DC generator worked by a falling object

I have done the following experiment: A DC generator is worked by an object falling and connected to the DC generator via string. The DC generator is coupled to a LED in reverse direction. The ...
2
votes
2answers
112 views

Is Galilei's reasoning on free fall valid?

Galileo Galilei discovered by experiments that all bodies tend to fall with the same rapidity (I use it in an intuitive sense, you can replace it by 'acceleration' used in today's physics language), ...
2
votes
1answer
460 views

What is the buoyant and viscous force acting on a ball in free fall?

I was thinking about a situation were I have a long cylindrical jar with some viscous liquid in it. I also have a spherical ball with me. I drop the ball into the liquid inside the jar with some ...
2
votes
1answer
465 views

Does the metal foam “whiffleball” orbital reentry idea make any sense?

Planetary Resources is a company speaking publicly about mining near Earth asteroids for resources. I'm interested the physicality of a claim they make in a video here: ...
2
votes
3answers
276 views

Why do objects fall at the same acceleration?

I read these two posts and now I am more confused. Do heavier objects fall faster? Don't heavier objects actually fall faster because they exert their own gravity? I was going to ask: if mass ...
2
votes
3answers
266 views

Does GR imply a fundamental difference between gravitational and non-gravitational acceleration?

Does the equivalence principle imply that there is some fundamental difference between acceleration due to gravity and acceleration by other means (because there is no way to 'feel' free fall ...
1
vote
3answers
1k views

Why is heavier object more reluctant to get falling down?

Is it because of the upward force that stops the object? for example-
1
vote
2answers
197 views

Do heavier objects fall faster? [duplicate]

This question has been asked multiple times here and all over the internet yet I can't find a conclusive answer: Some claim that heavier objects do fall faster: Don't heavier objects actually fall ...
1
vote
2answers
199 views

Should the cold drink come out of a free falling bottle with an open lid?

If I hold an open bottle and perform free fall, say sky diving, along with it from, say 10000ft, while I'm holding the bottle vertically upwards should the cold drink come out of the bottle? Kindly ...
1
vote
4answers
104 views

Bouncing ball time problem

I'm studying a problem and I encountered a strange problem: When a ball bounces how much time does the ball spend while touching the floor? To be more clear I suppose that when a ball bounces ...
1
vote
4answers
309 views

Freefall in/out of an enclosed environment

I've just been learning about Einstein, relativity, and the equivalence principle in Physics. I'm fascinated with the idea of being inside a free-falling enclosed environment (such as, e.g., rocket, ...
1
vote
1answer
83 views

Trajectory of falling object, with and without initial velocity

If an object is dropped from a roof with no initial velocity and wind is blowing along the side of the building exerting a constant force on the object, then its trajectory will be a straight line. ...
1
vote
2answers
223 views

Force on carabiner from free fall [closed]

Suppose I weigh about $75~\text{kg}$ and I am attached to a (non-elastic) rope which is attached to a carabiner which can take at least $20~\text{kN}$. Suppose furthermore that I reach terminal ...
1
vote
1answer
38 views

Measuring mass by acceleration due to electromagnetic forces in free fall

My question is a simple one (I think): How precise will the results be if you attempt to measure the mass of a macroscopic object by measuring it's acceleration when a constant electromagnetic force ...
1
vote
5answers
58 views

Why is acceleration constant in this example?

I was shown this video by our professor: https://www.youtube.com/watch?v=8A7DiGzJUvg&feature=youtu.be And I do not understand why the acceleration is constant. Our professor told us that a freely ...
1
vote
1answer
365 views

Gravity and free fall

In Wikipedia it's stated that "[..] gravity, is the natural phenomenon by which physical bodies appear to attract each other with a force proportional to their masses". Then I found many examples ...
1
vote
3answers
1k views

when an object moves downward, is its height negative?

the question is: A ball is thrown directly downward with an initial speed of 8.00m/s from a height of 30.0m. After what time interval does it strike the ground. so i went through the problem and ...
1
vote
1answer
213 views

How do I factor in multiple forces into these Newtonian mechanics equations?

Say a person is walking along. He then jumps. The person weighs $25$kg (irrelevant?). Just after jumping, his velocity is 5m/s (positive is taken as up). Gravity is taken as ...
1
vote
1answer
1k views

Trajectory of projectile thrown downhill

I'm teaching myself mechanics, and set out to solve a problem determining the optimum angle to throw a projectile when standing on a hill, for maximum range. My answer seems almost plausible, except ...