Explanation

• A pair of unlike parallel forces (forces that act in opposite directions) with different lines of force produce a couple.
• It is also known as a moment or torque.
• This is a rotational force that tends to cause rotation around a pivot point or axis.

Last verified on 26-10-2026

Explanation

• Newton’s First Law of Motion is also called the Law of Inertia.
• It states that an object remains at rest or continues moving at a constant velocity in a straight line unless acted upon by an unbalanced external force.
• Inertia is the tendency of an object to resist changes in its state of rest or motion.
• Proposed by: Sir Isaac Newton in Principia Mathematica (1687).

Last verified on 15-10-2026

Explanation

• The Moon is Earth’s only natural satellite.
• Diameter – 3,474 km
• Distance from Earth – 384,400 km
• Orbital period – 27.3 days
• Surface gravity – 1/6th of Earth
• First human landing – Apollo 11, 1969

Last verified on 18-03-2026

Explanation

• Zero error is a Systematic error because it causes a consistent error in every measurement.
• It occurs when an instrument does not read zero even when no quantity is being measured.
• The same error is repeated in all readings unless corrected.
• Zero error may be positive or negative.
• It can be corrected by applying a zero correction.

Last verified on 06-07-2026

Explanation

• Solar and wind energy are renewable sources of energy, meaning they are sustainable and will not run out.
• Solar energy is generated from the sun's rays.
• Wind energy is generated from the wind.

Last verified on 09-02-2026

Explanation

The renewable energy sources are:

• Water energy
• Wind energy
• Tidal energy
• Solar energy
• Hydroelectric
• Ocean energy
• Geothermal energy
• Biomass
• Biogas

The non-renewable energy sources are:

• Fossil fuels or Hydrocarbon fuel (Oil, Natural gas, Coal)
• Nuclear energy

Last verified on 16-03-2026

Explanation

Definition: Possess both magnitude and direction.

Representation: Represented by arrows, where the length indicates magnitude and the arrowhead indicates direction.

Examples: 

• Displacement
• Velocity
• Acceleration
• Force
• Momentum

Additional information 

Difference from Scalars: Unlike scalars, which only have magnitude (e.g., speed), vectors require both to be fully defined

Last updated on 09-03-2026

Explanation

• Weight is a vector quantity
• Because it is a force defined as the product of mass and the acceleration due to gravity (W = mg).
• It has both magnitude (amount of force) and direction (downward, towards the center of the Earth)

Additional information 

Mass,  Time, and temperature are scalar quantities

Last updated on 09-03-2026

Explanation

Scalar quantities are physical quantities that have only magnitude (amount or size) but no direction.

Examples of scalar quantities include:

• Mass
• Temperature
• Time
• Energy
• Distance

Last verified on 07-02-2026

Explanation

The mass of Earth is approximately 6.0 x 10^24 kilograms (5.98 x 10^24 kg).

This is a widely accepted scientific value, based on various measurements and calculations, including:

• Gravity measurements
• Satellite orbits
• Seismological data
• Planetary formation models