Brian Cox visits the world's biggest vacuum | Human Universe - BBC

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Recommends Phoenix87 · 2015-02 · Physics Stack Exchange · on “Why am I not accelerated by the reaction force applied by Earth on me?”

In a nutshell you should think that the Earth is accelerating upward and you are caught up in this accelerated motion since you stand in Earth's way perhaps this video can help a bit [this video]

Recommends Selena Ballerina · 2015-08 · Physics Stack Exchange · on “Where does light go after it enters a black hole?”

@developerwjk ".... understand that the question you've been asking is too complicated - let me show you a simpler question, answer it and prove it amounts to the same thing!". And that is the opposite of trivializing something. Listen to Brian Cox [this video] and his summary at the end of Einstein grasping the equivalence principle, that ultimately leads to GTR: what Einstein described as the happiest moment of his life was understanding "nothing special is happennning. To fall is natural. To fall is to be in the simplest motion state possible". That's ...

Recommends hsinghal · 2016-06 · Physics Stack Exchange · on “Gravity - What happens when two objects of unequal masses fall freely towards the ground? (Revisited)”

why dont you watch this video [this video] on experiment of free fall. I found this highly entertaining. Enjoy watching, Hope you will get your answers

Recommends M. Enns · 2016-07 · Physics Stack Exchange · on “How does atmospheric pressure affect the speed of object?”

No, a feather dropped in a vacuum jar will not drop at the same speed as in air. There must be a thousand video's out there of this very topic but my favourite is this one [this video] . An object moving through air, or any fluid, will experience a drag force [LINK] resisting its motion. This force increases as the speed of the object through the fluid increases. It also increases with the density of the air. Lower air pressure means less drag force. For a falling feather this would mean a larger terminal speed. For a train in a tube this would mean less force required to drive the train at a given speed.

Recommends rob · 2018-06 · Physics Stack Exchange · on “Why are non-equally heavy objects falling at the same speed on the moon?”

You might like this video of a bowling ball and a bunch of feathers dropped simultaneously in a large vacuum chamber [this video] .

Cites qmd · 2015-01 · Physics Stack Exchange · on “Is it correct to say that falling object are standing still?”

As I was browsing youtube I came across the BBC video " Brian Cox visits the world's biggest vacuum chamber - Human Universe: Episode 4 Preview - BBC Two [this video] " He drops a bowling ball and a feather in a vacuum chamber and observes them hitting the ground at the same time. He then says: "The reason the bowling ball and the feather are falling together is because they are not falling, they are standing still, there is no force acting on them at all..." This doesn't make any sense to me. I was under the impression and have always been taught that the gravitational force $\vec{F_g}=m\vec{g}$ is the force that "causes" objects to fall. In addition, if there was no external force acting on the

Cites Crusaderpyro · 2016-11 · Physics Stack Exchange · on “Does air resistance increase the speed of a falling object?”

I just saw an experiment where a heavy object (bowling ball) and a light object (feather) are dropped in a vacuum and they both fall at the same speed (almost like a slow motion video) and reach the bottom at the same time. But when the same two objects are dropped in a non vacuum environment, the ball hits the ground immediately while the feather has not even covered half the distance. I know this is somehow related to air resistance and terminal velocity and he air resistance reduces the acceleration of the ball to zero. but what I do not understand is that how come air resistance helps in increasing the speed of the ball ? Isn't it a kind of resistance ? Is it that in the vacuum experimen

Cites John Rennie · 2016-11 · Physics Stack Exchange · on “Mass and Period in circular motion?”

The reason for this is the same reason that (ignoring air resistance) all masses fall at the same speed. From Newton's second law we get an expression for the acceleration of an object of mass $m$ subjected to a force $F$: $$ a = \frac{F}{m} $$ The gravitational force on our mass $m$ is given by Newton's law of gravity: $$ F = \frac{GM_\text{Earth}}{r_\text{Earth}^2}\,m = g\,m $$ And combining these gives the acceleration: $$ a = \frac{gm}{m} = g $$ So regardless of the mass the acceleration has the same value of $GM/r^2$, which is the well known gravitational acceleration of about $9.81$ m/s$^2$. This means the motion of the object under gravity is independent of the mass, as (allegedly) pr

Cites tpk · 2017-08 · Physics Stack Exchange · on “Experimentally verifying some facts”

What are some thought experiment/real life experiment to convince me these two facts, so that I can test them actively: Fact-1: a. The speed of a falling body is non constant, and is increasing. b. Also, two bodies with different masses falls at the same speed. (Note that a. I don't own this [this video] room b. I don't have photoelectric (or whatever sensor they use to measure interruption in a beam of light to measure speed) sensor :) How do I be sure of these facts ? For the first part, I think I need some very very big height to test this, but I can't attain that much height. For the second part, I am having difficulty testing that as almost everything doesn't work in the long run (i.e there'

Cites JK Rolling · 2017-11 · Physics Stack Exchange · on “Gravitational force on two/three objects”

I've just seen the part of the BBC documentary Human Universe titled "Brian Cox visits the world's biggest vacuum chamber" (Episode 4) [this video] , made in cooperation with NASA in the biggest vacuum chamber in the world. They made an experiment to prove that a bowling ball (~3 kg) will "came down exactly the same" as a bunch of feathers (I would say ~0.1 kg). I think this is not true, probably due to Newton's law of universal gravitation. I would like to know what is the time difference between those two objects hitting the ground. The height is 20 meters. It would be also great to include the force of gravitation of all of the 3 objects in the experiment, because I think that a gravitational