Slide 1: 01 Thrust & Pressure project date 26/10/2010 Presented by Deepak Saxena Class : 9th ‘B’ Slide 2: DEFAULT STYLES 04 Gravitation The force of attraction between any two object can be said as gravitation .
There is one universal law of gravitation by Newton . Slide 3: DEFAULT STYLES 04 Universal Law Of Gravitation By Newton Universal law of gravitation states that every object in the universe attracts every other object with a force directly proportional to the product of their masses and inversely proportional to the square of their distance. Slide 4: Profement Slide 5: DEFAULT STYLES 04 Importance of universal law of gravitation The law explains that :
The force bind us to the earth.
The motion of the moon around the earth .
The motion of earth the sun.
The tides due to sun and the moon. Slide 6: DEFAULT STYLES 04 Freefall Whenever the objects fall toward the earth under its force alone then it is said that freefall is taking place.
For example :
Take a stone
Throw it down from the building
Here the action taking place can be said to be as freefall Slide 7: DEFAULT STYLES 04 Mass The mass of an object is the measure of it inertia .
Characteristics of mass:
The greater is the mass greater is the inertia.
The mass of an object is constant
Mass do not change from place to place Slide 8: DEFAULT STYLES 04 Weight The force of attraction on the earth on an object is known as the weight of the object .
Characteristics of weight :
The si unit of weight is Newton ( N ).
It is the force that acts vertically downward.
it has both magnitude and the direction . Slide 9: . DEFAULT STYLES Thrust The force acting on an object perpendicular to
the surface is called as thrust. Slide 10: DEFAULT STYLES Example: We wish to fix a poster on a bulletin board . To do this task we need to press the drawing pins through our thumb . It is seen that we apply force on the surface area oof the pin’s head. This force is directly perpendicular to the surface area of the board . Slide 11: DEFAULT STYLES Conclusion : Here by this activity we can observe that there is thrust force acting upon it i.e; the object ( pin ) is perpendicular to the surface ( board ) . Slide 12: DEFAULT STYLES 04 Pressure Force that acts on unit per area is said to
Hence we can write pressure as :
= Thrust/Area Slide 13: DEFAULT STYLES 04 Fluids All liquids and gases are said to be Fluids . Slide 14: DEFAULT STYLES 04 Pressure in fluids As we all know that solids exerts pressure . In same way fluids have weight and they also apply pressure on the base as well as the walls of the container in which they are to be kept .
Hence we can say that the fluids exerts pressure . Slide 15: DEFAULT STYLES 04 Buoyancy firstly let me ask a question to you . Have you ever swim in water and had felt lighter then that you are .
Here is the answer to my question “buoyancy” I c am going to explain to you that what is buoyancy and its factors . Slide 16: Activity: Take an empty bottle, a bucket filled with water .
Now take the bottle and push it down in the water.
Do you feel that something is pushing that bottle towards you .
Now try to sink the bottle as deeper as you can.
The jumps and came out .
So friends from this activity we had observed that there is certain force that pushes the objects upward in the water , this force is said to be the up thrust or the buoyancy Slide 17: DEFAULT STYLES 04 Why do objects sink or float in water To show this we need to perform one more activity here we are:
Take a glass filled with water .
Take an iron nail , foam place them on the water.
So we observed that the nail sinks . This because the force by the nail was greater than that of the up thrust .
But the foam was floating on the water this was happened because the force of foam was equilent to the up thrust. Slide 18: DEFAULT STYLES 04 u Text box Slide 19: Bullet Point
Sub Bullet 05 BULLET STYLES