Explanation

• The amplitude of a sound wave determines its loudness.
• Greater amplitude generally produces a louder sound.
• While smaller amplitude produces a quieter sound.

Additional information:

• Frequency: Determines pitch (high or low sound).
• Wavelength: The distance between two consecutive points in the same phase, such as two crests.

Last verified on 15-10-2026

Explanation

• A velocity–time graph shows how velocity changes with time.
• The slope gives acceleration.
• The area under the graph represents motion covered.
• It connects velocity with displacement.

Last verified on 22-05-2026

Explanation

• The speed of sound is generally maximum in solids.
• Because their particles are closely packed and elastic forces transmit vibrations rapidly.

Additional information:

• Solids: Sound generally travels fastest, e.g., Steel: 5,000–6,000 m/s
• Liquids: Sound travels slower than in most solids, e.g., Water: 1,480 m/s
• Gases: Sound travels slowest under ordinary conditions, e.g., Air at 20°C: 343 m/s

Last verified on 15-10-2026

Explanation

• Earth is called the Blue Planet.
• About 71% of Earth's surface is covered by water.
• Water makes Earth appear blue from space.
• Earth is the third planet from the Sun.
• Earth’s natural satellite is the Moon

Last updated: NA on 26-09-2026

Explanation

• The Theory of Relativity was proposed by Albert Einstein.
• It was introduced in the early 20th century.
• It includes Special Relativity (1905) and General Relativity (1915).
• The theory explains the relationship between space, time, and gravity.

Last verified on 02-04-2026

Explanation

• Venus is the brightest planet in the night sky.
• Due to its thick cloud cover that reflects sunlight strongly.
• It is often called the “Evening Star” or “Morning Star.”

Additional information:

• Distance from Sun: ~108 million km
• Diameter: 12,104 km
• Orbital Period: 225 Earth days
• Atmosphere: Thick CO₂ clouds, very reflective

Last verified on 15-01-2026

Explanation

• Cause: Mainly due to sulfur dioxide (SO₂) released from burning fossil fuels like coal and oil.
• Effect: SO₂ reacts with water vapor in the atmosphere to form sulfuric acid, causing acid rain.

Last verified on 08-02-2026

Explanation

• 1 Nanometer (nm) = 10⁻⁹ m (1 × 10⁻⁹ m)

Additional information:

• 1 Kilometer (km) = 10³ m
• 1 Meter (m) = 10⁰ m
• 1 Millimeter (mm) = 10⁻³ m
• 1 Micrometer (µm) = 10⁻⁶ m

Last verified on 06-07-2026

Explanation

• Gaps are provided between railway rails to allow for thermal expansion during hot weather.
• Metal rails expand when their temperature increases and contract when their temperature decreases.

Additional information:

• Scientific principle: Expansion of solids due to heat
• Effect of excessive heat: Rails may buckle
• Effect of cooling: Rails contract

Last verified on 12-10-2026

Explanation

• Velocity is a vector quantity. 
• A vector quantity has both magnitude and direction.
• Velocity, which describes the rate of change of position in a specific direction.
• It needs both a magnitude (speed) and a direction to be fully defined. 
• Vector Quantities: Velocity, momentum, torque, acceleration.
• Scalar Quantities: Work, distance, speed, mass.

Last verified on 12-10-2026