Light year is the unit of distance. One light year = 9.46 x 10¹² km.
Astronomical Unit (AU) is equal to the average distance between the sun and earth. It is 1.496 x 10⁸ km.
Parsec is the unit of distance and
1 parsec = 3 x 10¹⁶ m.
Oil rises due to capillary ascent in the wick of a lamp. It happens due to surface tension.
Planck’s constant and angular momentum have the same units.
In a uniform circular motion there is a change in both amplitude and velocity but the speed remains constant.
The atmospheric pressure at sea level is 1 bar.
An instrument that marks the changes in the atmospheric pressure, in a certain time interval, on the paper is called Barograph.
Manometer is an instrument that measures the pressure of a gas.
Retro rockets are used to reduce the speed of a space ship.
Vikram Sarabhai space centre is in Trivandrum.
Neil Armstrong was the first person to land on moon.
Lunic-II was the first space ship to land on moon.
The average density on earth is 5.5 cm³.
The weight of an object increases on taking it from the equator towards the pole at sea level.
Rain drops are spherical due to surface tension.
Nuclear radii are measured in Fermi.
1 fermi = 10-¹⁵ m.
The speed of a ship is measured in nautical.
1 naut = 1852 m/hr
Mercury is a liquid. It is alsoknown as quick silver. It is usedin thermometer, barometer, manometer and other instru-
ments.
The path of the Halley’s comet is elliptical.
Indian Institute of Astrophysics is in Kodai canal (Tamil Nadu).
Halley’s comet is seen after 76 years.
India’s first satellite was launched from the Rusia’s cosmodrome.
Length of days and nights are always equal at the equator.
National Science Day is celebrated on 28 February. This day is celebrated because the discovery of ‘Raman effect’ by C.V. Raman became known to the world on this day. Sir C. V. Raman was awarded with Nobel prize in 1930.
There is no force of attraction between the molecules of an ideal gas and hence, no energy change takes place on increase in its volume.
Goniometer is used to measure the angle of the crystal.
Purity of milk is measured by lactometer.
There is no change in the level of water due to the melting of ice in it.
Solar eclipse takes place when moon comes between the earth and the sun.
Lunar eclipse takes place due to the coming of earth between the sun and the moon.
Intensity of an earthquake is measured by Richter scale.
An earthquake is detected by a seismograph.
Fathom is the unit for measuring depth.
Greenwich time lags behind Indian Standard Time by 5½ hours.
There is no change in the mercury level when the radius of the tube in the barometer is increased.
Pascal is the unit of pressure.
1 pascal = 1 newton /m².
Flow of fluids is measured in Cusec which is equal to 1 cubic foot/sec.
1 cusec = 0.028317 m³/sec.
Electrons are present in all substances.
Water contracts on heating from 0°C to 4°C.
The time period of a second’s pendulum is 2 seconds.
A sudden fall in the barometer reading indicates a storm.
If the barometer reading gradually falls it indicates rain fall.
Ozone layer in atmosphere absorbs ultraviolet rays.
Anemometer measures the speed of air.
Altimeter is used to measure the height of planes.
Speed of air planes (or motor boats) is measured by Tachometer,
Periscope is used to see the objects outside the submarine.
Clouds float in air due the viscosity of air and their low density.
The coefficient of viscosity is measured in poise.
Viscosity of gases increases with temperature.
Soap decreases the surface tension of solution hence clothes get cleansed.
Needle floats on water due to surface tension.
The attractive force acting between the molecules of the same substance is called cohesive force.
The attractive force acting between the molecules of different substances is called adhesive force.
Rocket propulsion is based on the conservation of linear momentum.
A space traveller in a space ship revolving around earth feels weightlessness because the gravitational force acting on the ship is used in providing it the necessary centripetal force.
The moment of inertia in rotational motion plays the same role as the mass does in translational motion.
Colur of stars exhibits their temperature.
The product of mass and velocity of a body is called its momentum.
If a force is acting for a small duration, then the product of force and time is called impulse.
The change in momentum is equal to impulse.
The rate of change of impulse is equal to the force applied.
Relative density is measured by hydrometer.
When milk is skimmed, cream separates out due to the centripetal force.
If a hollow pipe passes across the centre of gravity of the earth and a ball is dropped in the pipe, the ball with execute SHM to and fro about the centre of the earth.
The periodic time of revolution around the earth of a communication satellite is 24 hours.
The value of bulk modulus for an incompressible liquid is infinite.
The viscous force limits the speed of the body falling in a liquid and it attains a constant velocity called the ‘terminal velocity’.
The order of the layers of atmosphere on moving up from the earth’s surface is troposphere, stratosphere, ozonosphere, Ionosphere, exosphere.
1 picogram 10-12 gram.
When a lift is moving up then weight of a person standing in it increases.
If a lift is falling freely the weight of a person becomes zero.
The weight of a body at poles is maximum.
The weight of a body at the centre of earth is zero.
If the velocity of a body is kinetic energy doubled its becomes 4 times.
The average density of earth is about 5.5 gm/cm³.
The frequency of oscillation of a simple pendulum decreases when it is taken on moon.
A floating iceberg instead of melting from the upper surface melts at the base because due to the higher pressure at the bottom surface the melting point decreases.
When speed of a car is doubled four times brake pressure has to be applied for stopping it.
Both impulse and momentum have the same dimensional formula.
On doubling the radius of a capillary tube the ascent of water in it becomes half.
Velocities of the rain drops of different sizes are different.
A pendulum clock becomes fast in winters.
Brass is an alloy of copper and zinc.
Man-made satellites are established in thermosphere (external atmosphere).
Stainless steel is an alloy of iron, nickel and chromium.
The velocity of escape from earth’s gravitation into space is 11.2 km/sec.
A feather and a piece of lead fall freely with the same velocity in vacuum.
Mass is a scalar quantity but weight is a vector quantity.
A body falling in a fluid acquires velocity due to the viscosity of the fluid.
Bernoulli’s theorem is based on energy-conservation.
1 light year = 9.46 x 10¹² km.
There is no atmosphere at moon because the rms velocity of gas molecules on it is greater than the escape velocity.
Density remains unchanged on changing the amount of a substance.
The speed of revolution of earth round the sun is maximum when earth is nearest to the sun.
Pure gold is of 24 carats.
Detergents decrease the surface tension of water due to which dirt and oil are easily removed from the clothes.
Parsec is a unit for measuring the distances of stars.
1 parsec = 3.25 light years.
Most of the weather disturbances take place in troposphere.
The study of friction and lubricants is done in Tribology.
A glass can be scratched by diamond or hydrofluoric acid.
For the dilution of sulphuric acid, acid is mixed in water and not water in acid.
F. Hile suggested that evolution of earth took place from gas and dust particles.
The extent of pollution of water in rivers is measured by the amount of oxygen dissolved in it.
A truck, car or motor cycle moving with the same kinetic energy will stop at the same distance on the application of brakes.
The tendency of a liquid drop to occupy the minimum surface area is due to surface tension.
Silver iodide is used for bringing artificial rain.
Diamond is an allotropic form of carbon.
Rocket works on the principle of conservation of momentum.
A solid iron ball floats on the surface of mercury because the relative density of mercury is greater than the relative density of iron.
The cause of the spreading of a drop of water on a clean glass plate is that cohesive force is lesser than the adhesive force.
Barometer was invented by Toricelli.
Theory of relativity was put forward by Einstein.
Air consists of maximum amount of nitrogen.
Atmospheric pressure is measured by barometer.
Steel is more elastic than rubber.
Purity of milk is tested by lactometer by measuring the density of milk.
The surface tension of a liquid is due to the cohesive force between its molecules.
The cause of atmospheric pressure on earth is the gravitational attraction.
The increase in barometer reading indicates fair weather.
The SI unit of work is joule.
The pressure inside a soap bubble is greater than the atmospheric pressure.
An iron needle floats on mercury but gets drowned in water because the density of iron is less than the density of mercury but greater than the density of water.
Oil spreads on the surface of water because the surface tension of oil is less than the surface tension of water.
It is difficult to walk on ice than on road because the frictional force on ice is lesser than on гоad.
Pendulum clocks become slow in summers because the length of the pendulum increases with increase in temperature, due to which the time period increases.
