# Tag Info

## New answers tagged free-fall

0

This scene was clearly shot with a stationary bus oriented (nearly) nose down and a green screen. A backpack and book are clearly dropped on the rider and accelerate at the normal rates. The rider hits seats and can't hold them as he falls. There is no way that air resistance on Earth could provide enough force to change the movement of the bus (and ...

3

No, no you guys (Except Floris and those who up-voted him) have missed an important observation... Look Carefully at the video again. At first the bus just tilts as the bridge bends. When the bus starts tilting (due to friction with the bridge it has not yet started falling) it has not yet obtained considerable vertical velocity. However as the man loses ...

1

First of all let's study an imaginary system where both the bus and the person are not subject to drag forces due to the air: If the person is not bounded to anything he will be subject to free falling and thus to a uniform acceleration $g$. Also the bus will be free falling and thus they fall together with the same velocity. If we take the drag forces into ...

37

The bus experiences considerable drag, and will therefore fall more slowly than a person inside the bus. The scenario is possible in principle - but after carefully viewing the clip and doing some calculations, I believe that the details are inaccurate. Assume the bus has a mass of 5000 kg (pretty light for a bus), and is 3 m wide by 3 m tall - so the ...

20

If the bus was in a vacuum (both inside and outside), then the passenger would float. However, the effects of air resistance on the two objects (passenger and bus) are probably not negligible in such an instance. The bus will be moving relative to the outside air, and so will be accelerating towards the ground at a rate less than $g$. If we then released ...

6

At first, the bus and the person would accelerate at the same rate due to gravity. However, the situation is more complicated due to air resistance. The bus experiences air resistance as it falls. The person inside the bus experiences less air resistance because the air inside the bus moves with the bus. This means that the person does not experience as much ...

0

I think the previous answers misunderstood the question. It's rather obvious that a balloon cannot have buoyancy in vacuum, and therefore cannot float into vacuum at steady speed. However, one needs to also consider the possibility that a balloon would achieve enough speed in lower atmosphere to bring it to 2nd orbital velocity. Imagine a huge light ...

-1

How can you explain objects of unequal masses falling at the same rate using GR? up vote By explaining why light curves, then by using the wave nature of matter to explain why an electron falls down, and then explaining that an ensemble of electrons (and other particles) falls down at a rate that is irrespective of the number of particles in the ensemble. ...

5

If Galileo had dropped the Moon and a pebble from a very tall tower, the Moon would have fallen noticeably faster, relative to the Earth. This is true in Newtonian physics as well as GR, and it does come from the fact that the Earth falls toward the Moon too, and harder than it falls towards the pebble. The assumption that small objects do not gravitate is ...

3

The strength of gravity is given by the space-time curvature caused by all the objects in the system, in this case both the earth and the falling object. The problem is that you are ignoring the fact that the space-time curvature caused by the earth is many, many times larger than that caused by the falling object. Hence, the total curvature is to all ...

0

Using any means of transportation I choose a Star-Trek grade transporter. I also taught sport parachuting for 10 years. As we can beam ourselves to any point we want, and do not have to be concerned with annoying orbital velocities, the re-entry speed is substantially reduced. Low-earth orbit will likely be no problem, and I'll sign up for it after a ...

2

The maximum speed possible for him to hit the ground form free-fall would be 11,200 m/s. This is the speed that he would have if you dropped him from "infinity". Therefore, if you can design a suit that can survive that then he can survive any height. 11,200 m/s is a very fast human but is a relatively slow meteorite. Apollo 11's re-entry speed was 103.71 ...

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