Physics

Sound waves travel fastest in media that are more rigid (have higher elasticity or bulk modulus) and have lower density. In general, sound travels fastest in solids, slower in liquids, and slowest in gases. Among gases, temperature also affects the speed of sound, with higher temperatures increasing the speed. However, when comparing media types, density and elasticity dominate. Dense solids like steel or glass allow sound to travel much faster than in less dense media like air. Therefore, sound waves travel faster in denser media (like solids) compared to less dense media (like gases).

Ole Rømer was the first to measure the velocity of light in 1676 by observing the eclipses of Jupiter's moons and noting discrepancies in their timing, which he attributed to the finite speed of light. The other options are incorrect or irrelevant.

The position of an element in the Periodic Table is determined by its atomic number, which is the number of protons in the nucleus of its atoms. Electron and neutron numbers do not determine the element's position.

The Earth's atmosphere is primarily composed of nitrogen, which makes up about 78% of the atmosphere by volume. Oxygen is the second most abundant gas, but nitrogen is the principal constituent.

The SI unit of electric current is the ampere, which measures the flow of electric charge per second. Coulomb is the unit of electric charge, and volt is the unit of electric potential difference.

Einstein's famous equation E = mc² expresses the equivalence of mass (m) and energy (E), with c representing the speed of light in a vacuum. This shows that mass can be converted into energy and vice versa.