Explanation

• Absolute Humidity is the actual amount of water vapor present in the air.
• Expressed as grams of water per cubic meter of air (g/m³).

Additional information:

• Relative Humidity is a percentage of maximum water air can hold.

Last verified on 06-02-2026

Explanation

• A wind vane (also called a weather vane) shows the direction from which the wind is blowing.
  • Usually installed on rooftops or meteorological stations.
  • Works with a rotating pointer that aligns with the wind direction.

Last verified on 01-02-2026

Explanation

S-waves are transverse seismic waves.

They cause particles to move perpendicular to the direction of wave propagation.

S-waves cannot pass through liquids or gases because these cannot support shear stress.

They only travel through solids, like the Earth’s crust and mantle.

This property helps scientists study the internal structure of Earth.

Explanation

P waves (primary waves) are the fastest seismic waves generated during an earthquake.

They travel through solids, liquids, and gases, compressing and expanding the material.

S waves (secondary waves) are slower and can only move through solids.

P waves are the first to be detected by seismographs.

Their higher speed helps in early warning systems for earthquakes.

Explanation

If Earth had no atmosphere, the sky would appear black even during the day,

Hence, the sky would appear black, just like it does from space.

Explanation

Decibel (dB) measures the intensity or loudness of sound.

It is a logarithmic unit, meaning each 10 dB increase represents a tenfold increase in intensity.

Decibels are also used in electronics and signal strength measurements.

It does not measure speed of light or heat.

Common examples: Normal conversation ≈ 60 dB, threshold of hearing ≈ 0 dB, jet engine ≈ 120 dB.

Explanation

• Comets are small celestial bodies made of ice, dust, and rock.
• When they approach the Sun, they form bright tails of gas and dust.

• Often called “dirty snowballs” due to icy composition.
• Comets follow highly elliptical orbits around the Sun.

Last verified on 19-01-2026

Explanation

One barrel of petroleum is a standard unit of measurement in the oil industry.

It equals 42 US gallons, which is approximately 159 liters.

In cubic meters, it is roughly 0.159 m³.

The UK gallon is larger, so one barrel equals about 34.97 UK gallons.

This unit is used worldwide for oil production, trading, and pricing

Explanation

This minimum required speed is called escape velocity.

Escape velocity of Earth is about 7 miles per second (≈ 11.2 km/s).

At this speed, an object can overcome Earth’s gravitational pull.

It does not depend on the mass of the rocket.

Escape velocity is crucial for space missions and satellites.

Explanation

Acceleration due to gravity on Earth is denoted by g.

Its standard value is 32 ft/s² (or 9.8 m/s²).

It acts downward toward the center of the Earth.

Gravity affects the motion of falling objects.

The value of g slightly varies with altitude and location.