Force And Pressure ( Quick Revision Notes)

 Hey, Learners today we are going to discuss about one of the most interesting topic of Physics that is Force and Pressure. 

So, Lets start the Topic.

1.Force- A push or a pull.

Our first topic of discussion is force. Then What is force? As you can see in the Heading Force is nothing but to push or pull of any object is reffered to as force. Due to force there is a change in the state of motion of any object. So if we elaborate this into perfect sentence.

In science, a push or a pull on an object is called a force. Thus we can say that the motion imparted to objects was due to the action of a force.

2. Force are due to an Interaction.

We have various examples through which we can easily say that we need at least two objects must interact for a force to come into play. Thus, an interaction of one object with another object results in a force between the two objects.

3. Exploring Forces.

Lets, Explore this topic with an example, Imagine that, there are two friends pushing a heavy load. In 1st condition they are pushing that load in the same direction and in 2nd condition they are pushing that load in the opposite direction. 

Forces applied on an object in the same direction add to one another.

But, the two forces act in the opposite directions on an object, the net force acting on it is the difference between the two force.

We learn that a force could be larger or smaller than the other or equal to each other. The strength of a force is usually expressed by its magnitude.

If the direction or the magnitude of the applied force changes, its effect also change.

4. A Force can Change the State of Motion.

Let's discuss this topic with an example, When a footfall player taking a penalty kick in football, The player applies a force due to this force the ball moves towards the goal.

But, before hitting the ball, it was at rest and so its speed was zero.

After this suppose that goalkeeper dives or jump to save the goal and if the goalkeeper succeeds in stopping the ball, its speed decreases to Zero.

After seeing this observation we can say that force applied on an object may change its speed.

If the force is applied in the direction opposite to the direction of motion, then it results in a decrease in the speed of the object.

A change in either the speed of an object, or its direction of motion, or both, is described as a change in its state of motion. Thus, a force may bring a change in the state of motion of an object. 

5. Force can change the shape of any object.

If you see in our surroundings there are various examples by which you can say that force can change the shape of any object. 

For Example:-

When we apply force on an inflated balloon by pressing it between your palms / When we press a rubber ball placed on the table and many more examples.

In all this examples we see that application of force on an object may change its shape.

* After learning all the previous topics we can say that:-

1. A force may make an object move from rest.

2. A force may change the speed of an object if it is moving.

3. A force may change the direction of motion of an object.

4. A force may bring about a change in the shape of an object.

5. A force may cause some or all of these effects.

6. Contact Force.

* Muscular Force:-

The Force resulting due to the action of muscles is known as the muscular foce.

ex:-  Muscular force of animals is used to carry out many difficult tasks.

*Friction Force:-

The force responsible for changing the state of motion of objects is the force of friction.

The force of friction always acts on all the moving objects and its direction of motion. That's why the force of friction arises due to contact between surfaces, it is also an example of a contact force.

  

7. Non Contact Force.

*Magnetic Force:-

Like Poles of Two magnet repel each other and unlike poles of two magnets attract each other. Attraction or repulsion between objects can also be seen as another form of push or pull.

The force exerted by the magnets is an example of a non contact force.

*Electrostatic Force.

The force exerted by a charged body on another charged or uncharged body is known as electrostatic force.

*Gravitational Force.

Objects or things fall towards the earth because it pulls them. This force is called the force of gravity, or just gravity. This is an attractive force. This force acts on all objects.

Every object in the universe either it is small or large have its own gravitational force.

8. Pressure.

The force acting on a unit area of a surface is called pressure.

pressure= force/area on which it acts.

9. Atmospheric pressure.

The envelop of air is known as atmosphere. The pressure exerted by this air is known as atmospheric pressure.

Let's Sum Up what we learned.

* Force could be push or pull.

* A force arises due to the interaction between two objects.

* Force has magnitude as well as directions.

* Force acting on an object may cause a change in its state of motion or a change in its shape.

* A force can act on an object with or without being in contact with it.

* Force per unit area is called pressure.

* Liquids and Gases exert pressure on the walls of their containers.

* The pressure Exerted by air around us is known as atmospheric pressure.