The document discusses friction and its various types including dry, fluid, skin, lubricated, and internal friction, highlighting its importance in resisting motion and energy conversion. It also introduces different forces such as magnetic, gravitational, frictional, electrostatic, and normal forces, explaining their roles and effects. Lastly, it covers how force is measured in newtons using a force meter, emphasizing the impact of forces on motion and shape changes.

1. Subject :- Physics
(Science)
Presented by:- Mayur
Godbole

2. FRICTION – IS THE FORCE RESISTING THE RELATIVE
MOTION OF SOLID SURFACES, FLUID LAYERS, AND/OR
MATERIAL ELEMENTS SLIDING AGAINST EACH OTHER.
There are 5 types of
friction:
Dry friction- it resists relative lateral motion of solid surfaces (in
contact). It is sub-divided into static and kinetic friction.
Fluid friction- it describes the friction between layers within a sticky
fluid that are moving relative to each other.
Skin friction- it is the force resisting the motion of a solid body
(through a fluid).
Lubricated friction- it’s a case of fluid friction where a fluid separates
two solid surfaces.
Internal friction- it’s a force resisting motion between the elements
making up a solid material while it undergoes.

3. Friction is one of the important part of nature. It is
necessary for us, the frictional force act as a “natural
stopper” if a ball thrown on the ground go in
any/specific direction it stops after sometime; it stops
because of frictional force acting on it. Friction can be
used i n m a n y w a y s :-
Due to friction no energy is destroyed (it act as a energy
consumer).
It is mostly used in converting kinetic energy into heat
energy.
It is helpful for a person who is lost in a forest, it can be
used to
generate fire on a wood.
Due to friction only we can write on a paper.

4. FORCES ARE ALSO DESCRIBED AS A PUSH OR PULL ON AN
OBJECT. THEY CAN BE DUE TO PHENOMENA SUCH AS GRAVITY,
MAGNETISM, OR ANYTHING THAT MIGHT CAUSE A MASS TO
ACCELERATE. SI UNIT OF FORCE IS NEWTON AND THE SYMBOL = F.
Different types of forces are:
Magnetic force
Frictional force
Gravitational force
Electrostatic force
Normal force

5. Magnetic force-
It is the force that attracts iron towards itself. We can see
magnetic force in magnet kept near iron pins.
Frictional force-
Frictional force is the force that opposes motion between two
surfaces.
Gravitational force-
The force that acts on the objects and pulls the objects
towards earth (due to gravity).
Electrostatic force-
It is the force which
Normal force-
It is a force that acts on an object experiencing 0 net
force, since his weight is balanced by a normal force exerted by the
ground.

6. Can you guess the following
forces:
Which force is acting on the
boy, after jump?
Which force is acting on
the rat ?
If the person (who is
cycling) stops paddling
then, which force will
act on the person and
the bicycle?

7. Newton SI
Dyne Kilo-pound Pound force Poundal
unit
1N ≡ 1 kg · m/s² = 105 dyne ≈ 0.10197 kp ≈ 0.22481 lbF ≈ 7.2330 pdl
1 dyne = 10−5 N ≡ 1 g·cm/s² ≈ 1.0197×10−6 kp ≈ 2.2481×10−6 lbF ≈ 7.2330×10−5 pdl
1 kp = 9.80665 N = 980665 dyne ≡ gn·(1 kg) ≈ 2.2046 lbF ≈ 70.932 pdl
1 lbF ≈ 4.448222 N ≈ 444822 dyne ≈ 0.45359 kp ≡ gn·(1 lb) ≈ 32.174 pdl
1 pdl ≈ 0.138255 N ≈ 13825 dyne ≈ 0.014098 kp ≈ 0.031081 lbF ≡ 1 lb·ft/s²

8. How do we measure force?
We measure force by using an instrument
Know as force meter (Newton meter).
Force usually act in pairs.
Force acts in a particular direction.
We measure force in newtons.

9. We can’t always
see the force.
We sometimes feel the
effects they have on things.
The balloon in the
picture is affected
by forces.
Forces can make things
Forces can make
speed up.
things slow down or
stop.
When you hit a tennis A parachute can make an object
ball it speeds up. slow down because of air
resistance.

10. Forces can make things change You can use a
direction. spanner to slacken
or tighten a nut.
You can make a cricket ball
change direction by hitting it with
a bat.
Forces can make things
turn.
Forces can make
things change shape.
If you squeeze or kick a football, it Forces are every where
will be compressed. !