CBSE Class 9 Answered

1. Point Masses: First let us understand what is a point particle. A point particle is an appropriate representation of any object whose size, shape, and structure is irrelevant in a given context. For example, from far enough away, an object of any shape will look and behave as a point-like object. Point mass is a particular type of point particles  whose only attribute is its mass. All other characteristics of a point mass are irrelevant in the given context.

 

eg a tennis ball in a large playground. It can be considered a 0-dimensional body with only a certain mass.

 

2.'G' in real life: A constant relating the force of the gravitational attraction between two bodies to their masses and their distance from each other in Newton's law of gravitation. The gravitational constant equals approximately 6.67259 × 10^-11 newton square meters per square kilogram.