1.
Class -9
Chapter-
Gravitation
Thrust and
Pressure

2.
The force applied on a surface in a
direction perpendicular to the surface
of an object.
SI unit newton
Thrust

3.
pressure
 The effect of thrust per unit area is called
pressure.
 Pressure =Thrust /Area
 Unit Pascal (Pa)
 1 Pa = 1N/1m2

4.
Pressure Depend On Two Factor
1. Force (thrust) - more force more pressure
2. Area - more area less pressure

5.
“The same force produce less
pressure if it acts on a large area
but can produce less pressure if
acts on a small area.”

6.
Every day
observation
1.school bag have wide straps so the weight
of bag may fall over a large area of the
shoulder of the student producing less
pressure on shoulder.

7.
Sharp knife cut better than a blunt knife so
the force of our hand fall over a very small
area of object produce large pressure.

8.
The tractor have broad tyres so there
is less pressure on ground and do not
sinking to comparatively soft field

9.
It is easier to walk on soft sand if we
have flat shoe rather than shoes with
sharp heels.

10.
The foundation of building and dams are
laid on larger area to produce less
pressure

11.
>The wooden or concrete sleepers are kept below
the railway line.
>A wide belt is provided over the wheels of an
army tank

12.
Home work /assessment.
1.Define thrust .What is its unit ?
2.What is relation between pressure , force and area ?
3.Name the quantity Whose one of the unit is pascal
(Pa)?
4.Why does a sharp knife cut objects more effectively
than a blunt knife ?
5.Why the tip of sewing needle is sharp?
6.Why snow shoes stop you from sinking into snow ?

13.
Thank - you