The inability of a body to change its state of rest or uniform motion along a straight line is called its

The submerged portion of the ice on melting shrinks a little in volume. so the level of water goes down a little.But this is just made up by the water added by the melting of upper portion. Addition is equal to the Shrinkage. Hence level is unchanged.

The Sound Following the flash of lighting is because of Thunder.

Lightning is seen earlier than thunder because light travels much faster than sound.

The roar of thunder is the result of a shock wave produced when lightning super-heats the air through which it passes, causing that air to expand very rapidly. This rapid expansion of air creates a shock wave that travels outward at close to the speed of sound.

A compass, which is used to assist in navigation, is an instrument that shows magnetic north. You must apply a correction to determine the direction of true north. The ability to steer a boat by a compass is useful if land is out of sight, visibility is reduced, or the boat operator is disoriented.

Mount a boat compass away from iron, magnets, and electrical wiring and equipment.

The light from the sun takes about 8 minutes to reach the Earth after it has been emitted from the sun's surface.

The time it takes for light to reach planets in our Solar System varies from about 3 minutes for Mercury to about 5.3 hours for Pluto.

The visible colors from Longest wavelength to Shortest wavelength are :: Red, Orange, Yellow, Green, Blue and Violet.

                    Red > Orange > Yellow > Green > Blue > Violet.

1. Infrared radiation has a longer wavelength than visible Red light.

2. Ultraviolet radiation has a shorter wavelength than the visible violet light. 

3. The white light is a mixture of the colors of the visible spectrum.

Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.

• Kepler?s three laws of planetary motion can be stated as follows:

(1) All planets move about the Sun in elliptical orbits, having the Sun as one of the foci.

(2) A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time.

(3) The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.

We know that,

The equivalent K =   L 1 + L 2 L 1 K 1 + L 2 K 2

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =   2 K 1 K 2 K 1 + K 2