Force and laws of motion class 9 , ncert chapter 9

www.upkarmarathi.com

Force and laws of motion.

Table of content 👇

1. What is force?
2. Effects of force
3. Types of forces
4. SI unit of force

|Force and laws of motion class 9 , ncert chapter 9

What is force?

•    Force is the pull or  push on an object. As we go further ,,,we can define the force as the push or pull on an object with mass that causes it to change its velocity is called as the force.
• Force is a vector quantity.
• eg:-to open or close the door of house or car.
• Kick the football
• Pull the trolley

Effects of force

• Force can move a stationary object
• Force can stop a moving object
• Force can change shape and size of an object.
• Force can change the direction of moving object.
• Force can change the speed of moving object.

Types of forces

There are mainly two types of forces. They are as follows

1. Balanced forces
2. unbalanced forces

Balanced forces

    Is the resultant of applied forces is equal to zero then it is called balanced forces.

eg

Unbalanced forces

   If the resultant of applied forces is greater than zero then it is called unbalanced forces.

eg-

SI unit of force

  

   As force is defined as the push or pull on an object with mass that causes it to change its velocity.

      F=ma

 Where F =force

              m= mass

               a= acceleration

SI unit of force is Newton. And it's symbol is  "N".

Spotlight

We can control the magnitude of the applied force and also its direction so force is a vector quantity just like velocity and acceleration.

Static is a branch of mechanics that deals with the forces acting on stationary object.

Dynamics is the branch of mechanics that deals with the cause of motion that is ,,forces acting on moving object.

A force exerted on an object can cause that objects velocity to change. that is, a force can cause an acceleration.

If you push a wall that is apply force on it the wall will not move ,this means practically a force does not always cause acceleration on an object.

The net force acting on an object is also referred  as the total force ,the resultant force or the unbalanced force acting on the object.

     

       An object is in equilibrium when it has zero acceleration. This means it is the state of an object or system of objects for which there are no changes in motion. It includes the state of rest as well as the state of uniform motion.

   The equilibrium rule-for any object or system of object in equilibrium the sum of the forces acting on it equals zero.