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

• Power is the rate of doing work or the rate at which energy is transferred.
• It is a scalar quantity (has magnitude only).
• It shows how quickly work is done.
• The SI unit of power is the Watt (W).
• 1 Watt = 1 Joule per second (1 W = 1 J/s).

Additional information:

• Formula: P = W/t = E/t
• SI Base Unit: kg·m²·s⁻³
• Dimension Formula: ML²T⁻³
• James Watt is the scientist after whom the Watt unit is named.

Last verified on 09-07-2026

Explanation

• Displacement is the straight-line change in position from an initial point to a final point.
• It is a vector quantity, having both magnitude and direction.

Last verified on 31-10-2026

Explanation

• At the center of the Earth, g = 0.
• Gravity from all directions cancels out at the center.
• So net gravitational force becomes zero.
• An object would feel weightless there.
• This is due to symmetrical distribution of Earth's mass.
• Earth’s surface gravity: 9.8 m/s²

Last verified on 17-06-2026

Explanation

• All electromagnetic waves travel through a vacuum at 3x10^8 m/s.
• This is the speed of light (c).
• Radio waves, microwaves, visible light, X-rays and gamma rays all have the same speed in vacuum.

Last verified on 31-10-2026