ICSE Class 9 Physics — Flashcards for Quick Revision

A: Measurement is the process of comparison of a given physical quantity with a known standard quantity of the same nature. A physical quantity is expressed as: Physical quantity = (numerical value) × (u

A: A unit is the quantity of constant magnitude used to measure magnitudes of other quantities of the same nature. Properties of a good unit: (1) Convenient size (2) Can be defined without ambiguity (3)

A: Fundamental units are independent of any other unit and cannot be changed or related to other fundamental units. Examples: metre (length), kilogram (mass), second (time). Derived units depend on funda

A: Scalar quantities are physical quantities that are expressed only by their magnitude. They need only unit and numerical value to be completely expressed. Examples: mass (5 kg), distance (10 m), speed

A: Vector quantities are physical quantities that require both magnitude and direction to be completely expressed. They need unit, numerical value, and direction. Examples: displacement (10 m east), velo

A: Distance is the total length of path through which a body moves. Characteristics: (1) It is a scalar quantity, (2) It depends on the path followed, (3) It is always positive, (4) S.I. unit is metre (m

A: Force is a physical cause that changes or tends to change either the size, shape, or state of rest or motion of a body. Two main effects: (1) It can change the state of rest or motion of the body (2)

A: Contact forces: Applied by making physical contact. Examples: (1) Frictional force (2) Normal reaction force. Non-contact forces: Experienced without physical touch. Examples: (1) Gravitational force

A: A body at rest remains at rest, and a body in motion continues to move with the same speed in the same direction, unless acted upon by an external force.