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It is believed that most major crowd disasters can be prevented by simple crowd management strategies. [20] Crushes can be prevented by organization and traffic control, such as crowd barriers. On the other hand, barriers in some cases may funnel the crowd toward an already-packed area, such as in the Hillsborough disaster.
In physics, there are equations in every field to relate physical quantities to each other and perform calculations. Entire handbooks of equations can only summarize most of the full subject, else are highly specialized within a certain field. Physics is derived of formulae only.
Spreads are a form of subsidence, in which a layer of material cracks, opens up, and expands laterally. Flows are the movement of fluidised material, which can be both dry or rich in water (such as in mud flows). Flows can move imperceptibly for years, or accelerate rapidly and cause disasters.
Catastrophe theory studies dynamical systems that describe the evolution [5] of a state variable over time : ˙ = = (,) In the above equation, is referred to as the potential function, and is often a vector or a scalar which parameterise the potential function.
What causes earthquakes? Earthquakes occur when the plates that make up the Earth's crust move around. These plates, called tectonic plates, can push against each other.
However, in formal technical discussions, when the size of the greenhouse effect is quantified as a temperature, this is generally done using the above formula. The formula refers to the effective surface temperature rather than the actual surface temperature, and compares the surface with the top of the atmosphere, rather than comparing ...
Classical mechanics is the branch of physics used to describe the motion of macroscopic objects. [1] It is the most familiar of the theories of physics. The concepts it covers, such as mass, acceleration, and force, are commonly used and known. [2] The subject is based upon a three-dimensional Euclidean space with fixed axes, called a frame of ...
[155] [156] The expansion of spacetime could cause the destruction of all matter in a Big Rip scenario. If our universe lies within a false vacuum , a bubble of lower-energy vacuum could come to exist by chance or otherwise in our universe, and catalyze the conversion of our universe to a lower energy state in a volume expanding at nearly the ...