Explanation

Speed of light in air (or vacuum) is approximately 3 × 10⁸ m/s (299,792,458 m/s), which is the fastest speed possible in nature.

Light slows down in denser mediums like water or glass due to interactions with particles, but in air, it remains very close to its speed in a vacuum.

Explanation

A wind vane, also called a weather vane.

It is an instrument used to determine the direction of the wind.

It typically has an arrow that points into the direction from which the wind is blowing.

Explanation

The speed of sound is higher in solids (like glass and iron) than in liquids (like water) and gases (like dry air).

However, the speed of sound in glass is less than in iron because iron is denser and has a higher elasticity.

Explanation

The Global Positioning System (GPS) was developed by the U.S. Department of Defense in 1973.

It was originally designed for military navigation but later became widely used for civilian purposes.

Explanation

Liquid-cooled garments were first developed for astronauts to regulate body temperature in space.

Now, they are also used by nuclear reactor workers and car racers to prevent overheating in extreme environments.

Explanation

The gear system helps control speed and force by changing the torque applied to the wheels.

The wheel and axle mechanism allows smooth movement and efficient transfer of energy.

Explanation

Paksat-IR was launched on August 11, 2011, as Pakistan’s first geostationary communication satellite.

It was developed with the help of China.

It provides telecommunication and broadcasting services.

Explanation

A black dwarf is the final stage of a low-mass star, after it has cooled and no longer emits significant heat or light.

It forms when a white dwarf loses all its residual thermal energy over billions of years.

Explanation

Explanation

Solar cells convert sunlight directly into electricity using the photovoltaic effect.

They are widely used in renewable energy systems due to their efficiency and sustainability.