The gravitational force between two masses is F. If the distance is tripled, force becomes MCQ with Answer and Explanation

Explanation:
Conservation of momentum applies to isolated systems with no external forces. In billiard ball collision on frictionless table, external forces (gravity, normal) cancel vertically, and no horizontal external forces act, so horizontal momentum is conserved. Book on table has zero momentum but no dynamic process. Falling ball has external gravity force. Accelerating car has external engine force. Thus only option B represents an isolated system where momentum conservation holds. Memory aid: Momentum conserved when net external force = 0. This conceptual question tests understanding of system boundaries and force analysis, crucial for mechanics sections in competitive exams.

Explanation:
F = qvB sinθ, max at θ=90°.

Explanation:
Convection involves bulk movement of fluid particles (liquid/gas). Conduction: vibration transfer without particle movement. Radiation: EM waves. Absorption is taking in heat.