2. • Inclined Plane
A common inclined plane is a ramp. Lifting a heavy
box onto a loading dock is much easier if you slide
the box up a ramp--a simple machine.
• Wedge
Instead of using the smooth side of the inclined
plane, you can also use the pointed edges to do
other kinds of work. For example, you can use the
edge to push things apart. Then, the inclined plane
is a wedge. So, a wedge is actually a kind of
inclined plane. An axe blade is a wedge.
• Screw
Take an inclined plane and wrap it around a
cylinder. Its sharp edge becomes another simple
tool: the screw. Put a metal screw beside a ramp
and it's kind of hard to see the similarities, but the
screw is another kind of inclined plane.
3. Lever
Any tool that pries something loose is a lever. A
lever is an arm that "pivots" (or turns) against a
"fulcrum" (or point). Think of the claw end of a
hammer that you use to pry nails loose. It's a
lever.
Wheel and Axle
Another kind of lever, the wheel and axle,
moves objects across distances. The wheel, the
round end, turns the axle, the cylindrical post,
causing movement.
Pulley
Instead of an axle, the wheel could also rotate a
rope or cord. This variation of the wheel and
axle is the pulley. In a pulley, a cord wraps
around a wheel. As the wheel rotates, the cord
moves in either direction. Now, attach a hook to
the cord, and you can use the wheel's rotation
to raise and lower objects.
6. Inclined Plane
The size of the effort force on the incline is
still less than the vertical lift.
3 N
5N
5 N5 N
7. Inclined Plane
Basically, an incline plane allows you to
decrease the effort force applied by
increasing the distance of the effort
force.
3 N
5N
5 N
5 N
8. Life, Force, and Motion
• Every time you move something,
use your pencil, or walk, you are
using force.
• Developing and growing plants
use force to grow, reproduce, and
survive.
• These forces are examples of
everyday life because that is what
a force is, everyday life.
9. Mechanical Advantage
• Mechanical
advantage of an
inclined plane is
the length of the
slope divided by
the height of the
plane, if effort is
applied parallel
to the slope
• So for our plane
MA = 15
feet/3 feet = 5
• Let’s say S = 15 feet, H =
3 feet
MA =
Length of Slope
Height of Plane
10. Inclined Plane
• The mechanical
advantage of an
inclined plane is
equal to the length
of the slope divided
by the height of the
inclined plane.
• While the inclined
plane produces a
mechanical
advantage, it does
so by increasing
the distance
through which the
force must move.
11. Tropisms
• A tropism is a growth response
involving bending or curving of a plant
part toward or away from an external
stimulus that determines the direction of
movement
• Response toward the stimulus is
positive, and response away from the
stimulus is negative
• An unbalanced force is needed to carry
out this biological process.
12. Phototropism
• Phototropism is the growth of stems of
plants toward light - it is probably the
best known of the plant tropisms
• phototropism is caused by elongation
of the cells on the shaded part of the
plant - so that entire plant bends or
curves toward the light
15. Gravitropism
Gravitropism is a response to gravity -
if a seedling is placed on its side, the
root will curve to grow downward and
the shoot will curve to grow upward
16.
17. Root Growth
• The main root of a plant typically
grows downwards towards earths
gravity.
• This downwards oriented growth is
termed gravitropism.
