Download Inclined Planes


With a large perpendicular force and a small
parallel force, the tendency to slide is very small.
An example of this would be a 15 degree slope.
The picture shown is a 30
degree slope, which
means that although the
perpendicular force is still
larger than the parallel
force the tendency to
slide is increasing!

The pink line in this
diagram shows the
parallel vector. This is the
vector that runs along the
plane. This is also the force
due to gravity. To solve for
this we can use the
formula Fgsin=Fg
Remember!
Keep in mind the
force of friction (Ff)
when solving for the
parallel force.

The red line shows
the perpendicular
force. This acts
into the plane.
Fgcos=Fg
In this direction we must
consider the normal force (Fn).
This is because the object is not
falling through the plane,
causing a balancing force
which pushes back up.
At this 30 degree
angle the weight
pushing into the ramp
is much greater than
the weight would be
on a 60 degree ramp.
This is in reaction to
the perpendicular
component.
However, as the angle is
increased the component
of the weight in the parallel
direction is increased.
Now, lets say we are using a machine to pull
a piano up a large ramp. The machine uses a
constant velocity. What must the
acceleration be?
 This is a trick question because a constant
velocity means that there is no acceleration!
The piano is being pulled at the same speed
the entire time.

What happens to the perpendicular
component as the angle is increased?
2) What happens to the normal force as the
angle is increased?
3) As the angle increases, the frictional
force will…
4) If the perpendicular force is large, the
tendency to slide is…
1)
5)
If there is constant velocity, the
acceleration is…
The normal force decreases.
2) It will decrease.
3) Change. It will decrease.
4) Very weak. This will become greater as
the perpendicular force becomes
smaller than the parallel force.
5) There is no acceleration with constant
velocity!!!
1)