2. Thrust
The force applied on a surface in a
direction perpendicular to the
surface
Unit = Newton (N)
3. Pressure
The effect of thrust per unit area is
called pressure.
Pressure =thrust/area
Unit – Pascal (Pa)
1 Pa = 1 N / 1m2
4. Pressure depends on two
factors
1.force(thrust)-more force more
pressure
2.area -more area less pressure
5. “The same force produces 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 bags 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 cuts better than a
blunt knife so the force of our
hand falls over a very small area
of object produces 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 shoes
rather than shoes with sharp
heels.
10. The foundations of buildings
and dams are laid on a 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. Now answer
Define thrust. What is its unit?
What is the relation between pressure, force
and area?
Name the quantity whose one of the unit is
Pascal (Pa)?
Why does a sharp knife cut objects more
effectively than a blunt knife?
Why the tip of sewing needle is sharp?
Why snow shoes stop you from sinking into
snow?
