Explanation

• Density is the mass per unit volume of a substance.
• Density is calculated by dividing the mass of a substance by its volume.
• The SI unit of density is kilogram per cubic metre (kg/m³).

Last verified on 25-10-2026

Explanation

• A scalar quantity has magnitude only and no direction.
• Speed tells us how fast an object moves, without specifying its direction.

Additional information:

• Velocity, acceleration, and force are vector quantities because they have both magnitude and direction.

Last verified on 31-10-2026

Explanation

• Mechanics is the branch of physics that studies the motion of objects and the forces acting on them.
• It includes kinematics (motion without considering forces) and dynamics (motion and its causes).
• Statics studies objects in equilibrium.

Last verified on 31-10-2026

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

• 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