is Friction
Friction a Force that always pushes
against an object when it touches
another object
When 2 things are in contact with
each other, there will be friction acting
between them
Friction
High friction (lots of friction) will slow
something down
Low friction (not much friction) will keep
things moving
High friction or Low friction?
Skis on the snow
Car tyre
Brakes on a bike
Water on a slide
Pencil and rubber
How can we reduce the friction
between 2 objects?
Reduce the contact area by using
rollers/ball-bearings/wheels
Change the surfaces of the materials that
are touching by using lubrication eg. Oil
Create a cushion of air
Eg. Like a hovercraft or air hockey table
Fluid Friction
This type of friction is what happens with liquids
and gases (In Physics, liquids and gases are
both called "fluids". They behave in similar
ways.)
Fluid friction is also known as "drag". On aircraft
it's also called "air resistance".
It depends on: how thick the fluid is
(its "viscosity")
the shape of the object
speed the of the object
Aircraft and car designers want to reduce
drag, so that the vehicle can go fast
without having to waste too much fuel.
How do you think they can do it?
Paper Aeroplane Competition
Aim:
The winning team is the one who gets their plane to stay in the air the longest and is
the fastest.
Materials:
1 sheet of blank paper
1 paperclip
Scotch tape
Instructions:
Use only the materials indicated in the above list; you dont have to use them all.
The plane may be constructed using all or part of the 21.5 x 28 cm sheet of paper.
Label each plane with the "engineers" name.
Each group is allowed three throws; record the best throw only.
Begin timing with the throw of the plane and end when the plane hits the floor.
Settle a tie with a throw-off.
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