Physics class 9
Chapter number 3
Dynamics
Definition of Dynamics: the branch of mechanics which deals with the study of motion with force it's effect and its causes.
Comprehensive questions
Question No 01
What is force? What are its units? Distinguished between contact in non-contact forces ?
Force: force is defined as push or pull of an object.
Quantity: force is a vector quantity.
SI unit: the SI unit of course is newton (N).
Representation: force is represented by (F).
Mathematically: F=ma
Types of forces: there are two types of forces.
The distingution between contact and non contact forces is given below.
1) contact forces: contact forces are those forces that acts when two objects physically touch each other .
These occur by real contact or direct contact between two objects.
Examples: pushing a book on the table or kicking a ball .
Other examples are friction force, Normal force etc.
2)Non contact forces: non contact forces are those forces that acts on objects without and you physical contact.
These forces can act at a distance.
Examples : gravitational Force, electronic force, magnetic force etc.
