Buoyancy is an upward force exerted by a fluid that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the column than at the top. This difference in pressure results in a net force that tends to accelerate an object upwards.

Explanation: The ability or tendency to float in water or other fluid. The power of a liquid to keep something afloat.

http://en.wikipedia.org/wiki/Buoyancy

Archimedes' principle indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics. Archimedes of Syracuse[1] formulated this principle, which bears his name.
Explanation: The weight of the displaced fluid is directly proportional to the volume of the displaced fluid. Thus, among objects with equal masses, the one with greater volume has greater buoyancy. http://en.wikipedia.org/wiki/Archimede’s

Principle Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in the floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects (e.g. water striders) to run on the water surface. This property is caused by cohesion of similar molecules, and is responsible for many of the behaviours of liquids. Explanation: The liquid molecules at the phase interface (gas-liquid, for example) interact with each other more than molecules in the gas phase. Especially if the gas phase is air or some other not very polar gas. This deforms the surface. Similar kinds of things happen at liquid-solid phase interfaces, like the wall of a glass capillary tube or a beaker. http://en.wikipedia.org/wiki/Surface

tension Laminar flow (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption between the layers.[1] At low velocities the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross currents perpendicular to the direction of flow, nor eddies or swirls of fluids.[2] In laminar flow the motion of the particles of fluid is very orderly with all particles moving in straight lines parallel to the pipe walls.[3] In fluid dynamics, laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.

Explanation: the flow of a viscous fluid in which particles of the fluid move in parallel layers, each of which has a constant velocity but is in motion relative to its neighboring layers. http://en.wikipedia.org/wiki/Laminar

Flow turbulent flow, type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, or mixing, in contrast to laminar flow, in which the fluid moves in smooth paths or layers. In turbulent flow the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction. The flow of wind and rivers is generally turbulent in this sense, even if the currents are gentle. The air or water swirls and eddies while its overall bulk moves along a specific direction.

Explanation: Movement of a fluid in which subcurrents in the fluid display turbulence, moving in irregular patterns, while the overall flow is in one direction. Turbulent flow is common in nonviscous fluids moving at high velocities. http://en.wikipedia.org/wiki/Turbulent

Flow A continuity equation in physics is an equation that describes the transport of a conserved quantity. Since mass, energy, momentum, electric charge and other natural quantities are conserved under their respective appropriate conditions, a variety of physical phenomena may be described using continuity equations.

Explanation: local form of conservation laws. Example : Conservation of mass-energy ,Conservation of linear momentum, Conservation of angular momentum Conservation of electric charge, Conservation of color charge Conservation of weak isospin, Conservation of probability http://en.wikipedia.org/wiki/Continuity_equation Bernoulli's principle states that, as the velocity of the fluid increases, its pressure decreases.

Explanation: it is when a fluid flows through a constriction, its velocity increases. When the velocity of fluid increases, the pressure drops. http://en.wikipedia.org/wiki/Bernoulli's_principle

The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the informal notion of "thickness".

Explanation: Thermodynamics is a branch of natural science concerned with heat and its relation to energy and work. It defines macroscopic variables (such as temperature, internal energy, entropy, and pressure) that characterize materials and radiation, and explains how they are related and by what laws they change with time. Thermodynamics describes the average behavior of very large numbers of microscopic constituents, and its laws can be derived from statistical mechanics. Explanation: Work can transfer energy to a substance, increasing the internal energy of the substance which can then decrease through the energy transfer by heat. The reverse process is possible. Energy can be transformed to a substance by heat and from the substance by work. Here, Thermodynamic processed are at play. http://en.wikipedia.org/wiki/Thermodynamics

Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.
Explanation: as temperature increases ,atomic vibration amplitude also increases. This tends to cause an increase in bond lengths and therefore leads to thermal expansion. http://en.wikipedia.org/wiki/Thermal_expansion The zeroth law of thermodynamics states that if two systems are each in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.

Explanation: When two objects are separately with a third object, they are in equilibrium with each other. Objects have the same temperature. http://en.wikipedia.org/wiki/Zeroth_law_of_thermodynamics#Zeroth_law_as_equivalence_relation
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