ICSE Class 9 Physics — Flashcards for Quick Revision

A: Measurement is the process of comparison of a physical quantity with a known standard quantity of the same nature.

A: A unit is a quantity of constant magnitude used to measure magnitudes of other quantities of the same nature.

A: Physical quantity = numerical value × unit. The numerical value shows how many times the unit is contained in the quantity.

A: A scalar quantity is a physical quantity expressed only by magnitude. It needs a unit and a numerical value, but no direction. Examples: mass, length, time, distance, speed, work, energy.

A: A vector quantity needs magnitude and direction to be complete. It is expressed using a unit, numerical value, and direction. Examples: displacement, velocity, acceleration, force, momentum, weight.

A: Given: 4 km east, then 3 km north Distance = 4 km + 3 km = 7 km Displacement forms a right triangle. Displacement = sqrt((4 km)^2 + (3 km)^2) Displacement = sqrt(16 + 9) km = sqrt(25) km = 5 km Answer

A: Force is that physical cause which changes or tends to change either the size or the shape or the state of rest or of motion of the body.

A: Contact forces are applied on bodies by making a physical contact. Examples: frictional force, normal reaction force, tension force in a string, and force exerted during collision.

A: Non-contact forces are experienced by bodies even without being physically touched. Examples: gravitational force, electrostatic force, and magnetic force.