Lecture Series on Classical Physics by Prof.V.Balakrishnan, Department of Physics, IIT Madras.
A force is a push and pull in a particular direction.
Force is a vector quantity and its SI unit is newton (N).
For force, the following two questions are very important:
(a) Which agent exerted this force ?
(b) On which object this force was exerted ?
For, example, if a person is standing in a storm, then he feels that a force is acting on him. Wind exerts force on the person and person experiences this force.
- With every force, point of application is associated.
- Each force that is exerted on an object is caused by a particular body in its environment. Like in above example, wind is exerting force on the person.
Force are classified in four categories:
(a) Gravitational force
(b) Electromagnetic force
(c) Nuclear force
(d) Weak force
We will discus about these forces, in detail in the corresponding units of the Focal Points.
In mechanics, we will mainly deal with contact forces, friction forces, spring force, tension in string etc, which all are electromagnetic in nature.
Before coming to the core part of this unit, we are discussing some objects used in applications of this unit like. String, Pulley and Spring.
String :-
Unless stated in the question, assume the string to be inextensible. The different blocks connected through an inextensible string would have same acceleration. If the string is extensible, the acceleration of different blocks connected through it would be different until the string can stretch.
Unless stated, assume the string to be light (negligible mass as compared to blocks/objects connected to it).
[ If string is massless, then tension in it would be zero. Pratically, a massless string is not possible.]
If string is having considerable mass, then tension at various points of string would be different.
To cause a tension in string, equal and opposite pulling force has to be applied at its two ends and tension in string is equal to either of the applied forces.
Pulley :-
Unless stated, assume the pulley to be light. The tension in the string on either side of a light pulley would be taken as same.
Unless stated, assume a pulley to be friction-less.
Force is a vector quantity and its SI unit is newton (N).
For force, the following two questions are very important:
(a) Which agent exerted this force ?
(b) On which object this force was exerted ?
For, example, if a person is standing in a storm, then he feels that a force is acting on him. Wind exerts force on the person and person experiences this force.
- With every force, point of application is associated.
- Each force that is exerted on an object is caused by a particular body in its environment. Like in above example, wind is exerting force on the person.
Force are classified in four categories:
(a) Gravitational force
(b) Electromagnetic force
(c) Nuclear force
(d) Weak force
We will discus about these forces, in detail in the corresponding units of the Focal Points.
In mechanics, we will mainly deal with contact forces, friction forces, spring force, tension in string etc, which all are electromagnetic in nature.
Before coming to the core part of this unit, we are discussing some objects used in applications of this unit like. String, Pulley and Spring.
String :-
Unless stated in the question, assume the string to be inextensible. The different blocks connected through an inextensible string would have same acceleration. If the string is extensible, the acceleration of different blocks connected through it would be different until the string can stretch.
Unless stated, assume the string to be light (negligible mass as compared to blocks/objects connected to it).
[ If string is massless, then tension in it would be zero. Pratically, a massless string is not possible.]
If string is having considerable mass, then tension at various points of string would be different.
To cause a tension in string, equal and opposite pulling force has to be applied at its two ends and tension in string is equal to either of the applied forces.
Pulley :-
Unless stated, assume the pulley to be light. The tension in the string on either side of a light pulley would be taken as same.
Unless stated, assume a pulley to be friction-less.
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