How can tall buildings (i.e. skyscrapers) support and hold all of the interior weight?
821158
it seems crazy that sky scrapers can be so high and not fall down on their own.  this is because it is full of materials that have been tested before to failure.  the structural engineer knows that every beam, joist or member has a certain design load capacity.\n\nby figuring out what the design of the building is, what materials will be used and what the different loads will act on the structure, the structural engineer will be able to adequately design a system that can carry the load.\n\nfor example.  a 5 story building is to be built.  the soil needs to be tested to see if it can support the foundation.  depending on how many people will load the floors, structural beams will be designed to support such loads and more.  most structural systems have been done and tested before so there is plenty of documented evidence that a certain structural system will work.\n\nnot to mention that many structural engineers now build their work virtually.  they can apply different simulations e.g. seismic loads to see if their calculations work and see it virtually withstand the loads.\n\nhope this helps.
1090548
Same as my previous answer except that a cantilever deals with negative moment although it makes no difference.  For hollow sections with the same Area as a I or solid rectangle would have much higher inertia because all of their mass is as far as possible from the centroid making for a very high EI and a very low deflection
291004
if an object is floating, the buoyant force on it equals its weight -- the vertical forces have to sum to zero.  try drawing a free body diagram to convince yourself of this.
129447
There is a point at which no structure can withstand an earthquake, but the main ways currently used are:\nA. The building has the ability to flex to some degree.\nB. They are constructed on large rollers or ball bearings.\nC. They are constructed on large hydraulic pistons or springs.\n\nThe Japanese lead in this technology.
726042
The most important thing is bend don't break, the tree method.  Therefore, wood and steel far outweigh brick.\n\nAnything that will allow for some movement, but not too much, and still retain strength, is good.\n\nMany buildings, especially very tall ones, either have ancors that are very deep below the ground level  or pivits which allow for some sway.
1078717
Yes, but not having a Boeing 747 crashed into them. They actually stood up for quite a long time with the fires and the structural weakening. No building is meant to withstand the magnitude of a crash from a Boeing 747 with a full tank of fuel. The steel inside should have actally expanded, but yet it stayed still long enough for most of the survivors to get out. I think the structural integrity weighs out the disaster. The twin towers weren't going to stay up forever, as with most skyscrapers they are very succeptable to the elemetns as well.
97277
The cranes used to construct skyscrapers are built onto specialized rails.  When the crane's height needs to be increased, another section of the rails are installed to the top of the existing rail structure.  The crane is then ratched up to the top of the next rail section thus placing it higher than the rest of the building.
1122044
They sell racks to hold those, either on the floor or hanging on the wall.  Try an artist store, or architect supply store. Even a store that copies blueprints.  Around here there is an Organized Living store and The Container Store, and they usually have systems that might adapt to holding them.
234529
well, it depends what you mean. for air mattresses and inflatables, they actually get heavier. cuz if theyre all folded and everything, then the total weight is just the weight of the object, but if you put air inside, then the total weight would be the weight of the object AND the weight of the air inside (air has a density of 1.1kg/m^3 or something). \nif you mean like, a solid cube of wood compared to a hollow cube of wood (or any other material), then the hollow one would generally weigh less because the density of air is a lot less than most things. if the density of the wood (or whatever) was less than density of air, then it would actually become heavier if you put air inside. \ndensity is the ratio of mass  to volume. \nso a oil has a higher density than water because a glass of oil would weigh a lot more than a glass of water if you had same amounts of both.\nhope this helps. let me know if you need more help. laterz
1144696
gravity and air resistance.
868889
No. You need high density material and mass to create a strong gravitational pull.
432088
*copied from previous post\n\nYour question is unclear about what set of assumptions you want to use. You seem to imply a perfectly constructed stool, with a perfectly centered force, using incompressible material. You want the stool to have no mass, and you imply that you want to use statics to solve this problem. Strictly applying statics, this system is indeterminate, NOT the ridiculous answer of 0 [N] in two legs and W/2 [N] in the others. There are only 3 equations of equilibrium here, 1 for vertical forces and 2 for moments. Since you have four legs, this system cannot be solved by statics alone. Treating the stool as a deformable structure, you can use geometric compatibility to get a fourth equation. I challenge you to find a competently built stool that has 0 [N] in any leg (a physical stool built of real materials), or an incompetently built stool with 0 [N] in any two legs (unstable system that is obviously not static). The answer indicated as "correct" requires an incorrect application of statics. A large part of studying physics is learning when to use a particular tool, and the physical limits of that tool.
679755
I would take half of the area between adjacent rafters and multiply by 220 to get the load in pounds for end rafters.\n\nI would take double that for interior rafters.\n\nThis assumes that you have the same spacing between all rafters.
1164443
A pyramid would be an good support for a load on top.  It would distribute the load to a broad base thereby allowing a low soil bearing pressure. However, if the load on top was of any height or subject to wind loads, the pointed top would have to be changed to provide a flat surface that could be used to anchor the load.  We seldom see pyramids as support structures because that would be too expensive to construct.  Instead we see columns, rectangles and other shapes in buildings or power lines.  In considering a structure to support a load, economy is important.  You have the right concept of supporting the load on a broad base if the soils are weak.
347555
Depends also if it is muscle or fat.  The muscle can overcome the inertia & air friction.
898102
There are several factors decides the amount of destruction during earthquakes. The safest place is only the open ground. Important factors are magnitude, frequency of earthquakes, and natural frequency of buildings, geographical condition, and the distance from the source of earthquakes. Some times tall building withstands the quakes and short buildings are damaged. If the frequency of earthquakes matches with the natural frequency of the building the damages will be more. You can construct the building of short height using the technology adopted for self alignment bearings. That will just osculate. No damages will be there for any quakes. Please visit my slide show in the following URL. \nhttp://asia.pg.photos.yahoo.com/ph/quake
1169302
Yes, gravity exists near anything that has mass.  If you remove the air from a container, what's inside won't float.