Firstly, you may have noticed that your body is in contact with the ground now. So, we are already there.

I think the question you mean to ask is how much more gravity would be required before you would be unable to stand or move about freely.

This largely depends on two things. How much do you weigh now, and how strong are you?

Most people experience trouble at 2G. The average person weighing in at 150lbs would weigh 300lbs. A healthy person could stand, but walking could cause major injury.

At 3G the same person would weigh 450lbs. Only a very strong person could walk. Most people could not move their bodies. Sick, elderly people and very young people may not be able to breathe.

At 5G the same person now weighs 750lbs. Only athletes would be able to maintain consciousness for more than a few minutes. Death would be certain for anyone exposed long term as their heart would be unable to circulate blood throughout their body, and most of your organs would fail under this pressure. Breathing would eventually break your ribs, which in turn would prevent your ability to breathe.

At 10G the same person now weighs 1,500lbs or 3/4 of a ton. Athletes would be unable to count to ten before lossing consciousness. Life would be unlikely sustained for an hour. Liquids within your body would seperate into different density materials within a short period of time.

At 20G the same person now weighs 3,000lbs or 1.5 tons. Life would be measured in seconds. Liquid displacement within your body would visibly show swelling in the lower portions of the body. Lower body parts would quickly turn black.

At 50G the same person now weighs 7,500lbs or 3.75 tons. You are near or at the limit of instant death. A typical person has a profile of 5.5 sqft. You now weigh enough that if you were to be placed on typical solid earth at 1G you might cause the dirt you were placed upon to start to collapse with you sinking as much as foot into the ground.

At 100G the same person now weighs 10,500lbs or 5 tons. Your bones easily push through your skin. Long term, even your bones will crumble under the strain. Your weight crushes most lightweight materials. It requires bedrock, stone, thick concrete or steel to support your weight.

First scenario, sound.

Because you are in a plane you are in a fairly sealed environment. The air around you is traveling roughly at the same speed you are traveling. As such, all sound and speech within the plane would appear normal to you as would the look of everything around you.

Second scenario, speed of light.

You, the plane and the person sitting ten rows back would be converted into energy. No speech no hearing.

Second scenario (b), just below the speed of light.

Because you are in a plane you are in a fairly sealed environment. The air around you is traveling roughly at the same speed you are traveling. As such, all sound and speech within the plane would appear normal to you. Things would look normal within the plane. Outside the plane, everything would seem to be speeding up compared to you (and the plane). By how much? Depends on how close to the speed of light you moving.

Roughly speaking; yes.

We lose a few tons per year from the atmosphere, we gain a few from debris falling onto Earth. But basically you can consider it constant.

The bigger problem tends to be water mixing with other materials so that we can’t readily use it as water. Or components of water being tied up in other materials.

It seems like we have less because of several major factors. 1. Lakes, rivers, and aquifers take a while to filter the water. 2. We have introduced new materials that need to filtered (pollution), in which some of these sources are not capable of filtering. 3. We have a lot more people and demands on these water sources than even a short time ago.

Ergo, same amount of water, harder to get water in the condition you want for your needs.

1′x10′

2′x5′

A little more than 3′x3′

Hold your arms out. That far all around you is about 10sqft.

This is a highly subjective question.

By scale:

The great wall of China

Three Gorges Dam

By cultural significance:

The Eiffel tower

The empire state building

Toyko tower

The great pyramids

Probably the best answer is any building/structure a small group of people could name off the top of their heads. But, I don’t think that was quite what you wanted.

The granite sink is carved or hollowed out granite. The composite will be a cement/concrete type construction using granite or similar material as the aggregate or filler.

The carved granite will be considered more luxurious, but composites tend to be better sinks, all other things being the same.

Simple answer, yes. This is called the heat island effect.

This is caused by a number of factors:

Albedo – The amount of reflected light (including UV and IR). This generally affects radiant heat in the area.

Thermal storage/ thermal lag/ insulation (also embodied heat/energy and specific heat) – The amount of heat present materials can absorb along with the rate at which they then release said heat back into the surrounding area. This is a complicated subject known as thermodynamics which gets really nasty at this level of complexity. This generally affects convection, contact and radiant heat in the area.

Wind change – Air will tend to get compressed between and above buildings causing wind speed changes. Changes in the air temperature will greatly affect the wind. This generally affects convection in the area.

Shade and shadow – By changing or denying areas to direct light you are changing the which objects get which heat/energy going into them. this greatly affects the radiant and contact heat in the area.

Great, what does all this mean?

We are replacing existing environments with increasingly higher reflective surfaces and better thermal storage systems. So, you get more energy shared during the day; more heat. And, better energy release during the night, more heat.

Most of the existing systems either just stored more energy, used the energy, or slowly transferred it into the ground. Modern materials either reflect it onto something else or release it back into the environment as soon as the temperature outside changes below its surface temperature.

Surface winds should decrease in both strength and velocity as the total temperature change is decreased.

Basically, if the total temperature range is smaller you should get less and slower wind.

Any height provided you met the emergency egress requirement.

In North American jurisdictions you need an emergency exit from bedrooms. If there is no exterior door, then you use a window. If you a window it can’t be more than 44″ from the floor.

There are many reasons why, but I’m going to assume you are asking about highrises for living and offices.

One of the better reasons is to allow more people on the same amount of ground.

Second, for economics.

Let’s say a given area currently has 1 family per acre. These are nice fairly open areas. But, if all the areas fill up with 1 family per acre, but more people want to come it stars to make since to place more families per acre.

Once you get to about 16 families per acre you need to change how you are placing people. The simple answer is to go up (usually going up is about 10 times easier than going down).

Again once go 5 levels up things change again.

Right now most conventional construction can take you up to about 60 levels above ground or about 15 levels below ground. Beyond that you start needing to get creative.

So, back to the question, the reason we build highrises is to allow more people to get together than would be possible standing on the ground.