The Force

1
The Force Friction
The Force Friction
of
of
2
Will a paper clip and a tissue fall with the
same speed and force?
NO!!! The tissue floats slowly, moving from
side to side. The paperclip falls straight down!
3
But if they weigh about the same, shouldnt the
force of gravity affect them the same?
Newton was very troubled by this! He went all
over, dropping objects to try to understand
the force of gravity!
4
One day, when Newton was dropping things off the
leaning tower of Pisa, he realized the
answer...
The force of gravity is the same everywhere!
The force of gravity is the same everywhere!
The objects fell with different speed and force
because...
.
.
.
.
.
.
5
...There was another force acting on some of
the objects!
Newton was so surprised!
(okay, maybe not THIS surprised!)
6
The other force is called Friction. Friction a
force that acts in the opposite direction of
motion!
Tissue
The force of the friction cancelled some of the
force of gravity!
2 N
5 N
7
As the tissue started to fall, it bumped into
some air molecules!
The air made the tissue have to move
around, and slowed it down!
8
This special kind of friction is called air
resistance!
Paper
2 N
Larger sized objects run into more air
resistance, and are slowed by the friction.
Small objects fall free!
5 N
5 N
9
Most friction happens when two objects touch.
10 N
1 N
10 N
4 N
The more contact there is, the greater the
magnitude of friction!
10
This is why round things dont slow down as much
when pushed less touching!
8 N
1 N
8 N
8 N
11
Rougher surfaces also cause more friction
because they act like lots of speed bumps!
9 N
10 N
8 N
1 N
1 N
1 N
12
This is why our skate shoes are flat with lots of
ridges!
The friction keeps us from sliding off our
skateboards!