2. Fric&on
• Fric&on
is
a
force
between
2
surfaces
that
are
sliding,
or
trying
to
slide,
across
each
other.
• Fric&on
always
slows
down
a
moving
object.
• Air
resistance
is
a
type
of
fric&on.

3. Fric&on
• Fric&on
is
a
force
between
two
surfaces
that
are
sliding,
or
trying
to
slide,
across
each
other.
For
example,
when
you
try
to
push
a
book
along
the
floor
fric&on
makes
this
difficult.
• Fric&on
always
works
in
the
direc&on
opposite
from
the
direc&on
the
object
is
moving,
or
trying
to
move.
Fric&on
always
slows
a
moving
object
down.
•

4. Fric&on

5. Fric&on
More
or
less
fric,on
• The
amount
of
fric&on
depends
on
the
materials
from
which
the
two
surfaces
are
made.
The
rougher
the
surface,
the
more
fric&on
is
produced.
Heat
• Fric&on
also
produces
heat.
If
you
rub
your
hands
together
quickly,
you
will
feel
them
get
warmer.

6. Air
Resistance
• Air
resistance
• Air
resistance
is
a
type
of
fric&on
between
air
and
another
material.
When
an
aeroplane
flies
through
the
air,
for
example,
air
par&cles
hit
the
aeroplane,
making
it
more
difficult
for
it
to
move
through
the
air.

7. Air
Resistance

8. Streamlining
• Some
shapes,
known
as
streamlined
shapes,
cause
less
air
resistance
than
others.
Aeroplanes
and
cars
are
streamlined,
so
that
they
move
through
the
air
as
easily
as
possible.

9. Streamlining

10. Fric&on
Experiment