GK for AIIMS- 3

This is my third release notes regarding the preparations you should undertake in order to clear the A.I.I.M.S.
Here I am featuring some questions regarding Scientists. Many of these were asked in the previous years papers.

*A petrol fire cannot be extinguished by throwing water on it because the heat of the petrol fire is so intense that the water thrown on it gets evaporated and decomposes quickly or since the density of water is more than the density of petrol, water sinks below the petrol when it is poured over a petrol fire.


*An iron nail floats on mercury but sinks in water because the specific density of iron is lower than that of mercury and higher than that of water.


*Ice floats on water but sinks in alcohol, because the specific density of ice is less than that of water and more than that of alcohol.


*As we go up in the atmosphere, the temperature and pressure decreases.


*If the pressure shown by a barometer rises, it indicates fair weather.


*The density of sea water is higher than the density of river water. Therefore it is easier to swim in the sea than in river. This is why a ship entering from river mouth to sea rises up a little.


*Mercury is used as the liquid in thermometers as it does not wet glass.


*Laws of gravitation and the laws of motion were discovered by Sir Isaac Newton, the author of 'Principia of Mathematica'.


*Inertia is the property or tendency of a body to resist any change in its rest or of uniform motion in a straight line. The word inertia was given by Galileo. The more inertia a body has, the greater is its mass.


*Quantum theory was presented by Max Planck for which he was awarded the Nobel Prize in 1918.


*Escape velocity is the minimum speed which a spacecraft must have to escape Earth's gravitational force. It is 7 miles/s. (11.2 km/s).


*The law of conservation of energy states that energy can neither be created nor be destroyed. It can only be changed from one form to another but the total amount of energy remains constant. This theory was formulated by Albert Einstein.


*A dew drop is spherical because a sphere has a minimum surface area and a dew drop tries to attain this surface area for its equilibrium.


*Raindrops are spherical due to surface tension.


*Anything that occupies space and possesses weight is called matter.


*The force of attraction between like molecules is called cohesion and the force of attraction between unlike molecules is called adhesion.


*Weight can be defined as the force with which the earth attracts a body. Mass remains constant while weight varies.

*Density is mass per unit volume of a substance.


*Friction is a force that resists the movement of one surface over another.


*'Tribology' is concerned with studying interacting surfaces in relative motion.


*Elasticity is the ability of a body to return to its original shape and size on the removal of the deforming force.


*Glass is more elastic than steel and steel is more elastic than rubber.


*The oil in the wick of an oil lamp rises due to capillary action.


*Solids retain their shape due to cohesion.


*Strain is proportional to the stress producing it and the ratio is constant for any given material. This is known as Hooke's law.


*Archimedes's principle (Principle of Buoyancy) states that the upward force acting on an object immersed in a fluid is equal to the weight of the fluid that is displaced by the body.


*The theory behind the lever and pulleys was first demonstrated by Archimedes.


*The hydraulic press and hydraulic breaking is based on Pascal's law which states that the pressure applied to an enclosed liquid is transmitted equally to all parts, whatever be the shape of the container.