gawas Sonam gosavi Neekita Bhowar FRICTION Friction is the force resisting the relative motion of solid surfaces fluid layers and material elements sliding against each other ID: 783480
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Slide1
FRICTION
By :-
L
eena
gawas
Sonam
gosavi
Neekita
Bhowar
FRICTION
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
Slide3Types of friction
Dry friction
:- is a force that opposes the relative lateral motion of two solid surfaces in contact. It is subdivided into
static friction ("
stiction"):- between non-moving surfaces. It exists between a stationary object and the surface on which it's resting.
Slide42) kinetic friction
:- between moving surfaces.
Also called as sliding friction
.
Eg. Rubbing both hands together to create heat
Slide5Fluid friction :- describes the friction between layers of a viscous fluid. Also called as viscosity.
Rolling friction:-
is a force that slows down the motion of a rolling object.
B
all or wheel has rolling friction when rolled on a surface.
Slide6Factors affecting friction
Types of surfaces
How hard the surfaces are pushed together
Mass of object
F=µN (N=mg)
Slide7Friction increases when the force between two objects is
increased
.
What increases
Friction
Slide8What increases friction
Rough surfaces
A pair of
rough surfaces
will have more
friction
than a pair of smooth
surfaces
, because the “peaks” of one
surface
can fall into the “valleys” of the other.
Weight of an object
Force friction= weight x coefficient of friction
So as the weight increases so does the amount of friction.
Slide9Friction increases when surface area of an objects increases
Slide10To reduce the amount of friction, apply a
lubricant
between two surfaces.
Motor oil,
wax, and grease are examples.Friction can also be reduced by rolling, rather than pushing, an object.
What decreases
Friction
Slide11Slide12Measuring Friction
M
easuring
friction have been investigated for more than 2500
years.
Amonton's
law was
originally
published
by
Da
Vinci and
later
rediscovered by
Amonton
.
Amonton's
law
states that
the
friction depends only on the force normal to the contact plane. From this, the friction
coefficient
can be defined as:
μ=
F / N
where
F is the force required to move an object on a horizontal surface and N is the load normal
to the surface.
Slide13Friction Measuring Equipment
T2GO Portable Continuous Friction Measuring Equipment, CFME
T2GO, which can measure friction on any surface both dry and contaminated. It is ideal for measuring in areas where it might be difficult to get access to with a larger trailer or vehicle type friction tester.
Slide14A
n essential tool in the operation of traffic infrastructure during winter conditions.
This serves as a guidance to initiate remedying actions such as snow removal, distribution of de-icing chemicals and speed reduction, in order to enable a safe use of the traffic infrastructure.
Slide15Friction in plants
The stability of twining vines under gravitational loads suggests an important role for friction.
The coefficient of friction, μ, between vine stems and wood is high, often five times greater than between leather and wood.
Slide16An interesting difference in frictional properties was the upright hairy segments had larger frictional interactions than the inverted hairy segments.
Slide17FRICTION IN ANIMALS
Many animals have the natural ability to move on vertical walls and ceilings.
They attach to surfaces using claws, soft and hairy pads.
Recent studies have indicated that the frictional forces generated by these structures not only control the movement of animals but also significantly increase the reliability of their attachment.
Slide18Snakes use Sliding Friction as they slither along. They use branches and sticks to push and slide along the ground or in trees.
In fact their scales are perfectly designed to keep the snakes from sliding backwards or
sideways while
climbing
Slide19Snails use fluid friction as they give out slime layer to protect their body from rough surface and improve movement.
It also acts as shield against parasites.
Slide20Flies, geckos and beetles have ability to move on inclined surface using hairy pads.Soles of feet have elastic epidermis covered with setae which control friction and
genertes
opposite frictional forces.
Slide21Snapping turtles great size makes it impossible for predators to prey on them unlike small turtles.
Static friction makes it harder for turtle to be moved by predator.
Slide22The body of the mother-of-pearl moth caterpillar escapes predators by anchoring its tail, recoiling, and uses rolling friction for escape.
By turning into a wheel, the caterpillar moves some 40 times faster than its normal walking pace.
Slide23Uses of friction
When surfaces in contact move relative to each other, the friction between the two surfaces converts
kinetic energy into thermal energy
(that is, it converts work to heat).
This property can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood or stones together to start a fire
Slide24In space, meteors and comets have no force to slow them down. As they hit the Earth's atmosphere, however, not only does the atmosphere's friction slow them down, it tends to break them apart into smaller pieces, thereby lessening their impact on the Earth's surface.
Slide25THANK YOU