Transcript Teacher Page - Sikeston R-6

Teacher Page
•IV. Force, Motion and Mechanical Energy
•C. Interactions of force and motion
•State Standards 1.1; 1.6; 1.10; 3.1; 3.6; 4.1
•7th grade assessment
•Students should be able to explain and demonstrate how common
tools are simple machines and discuss the forces and motions
involved.
•View lesson before using with students. Sample questions and
answers appear with mouse click or automatically.
What are the six basic
kinds of simple
machines?
• Inclined plane
• wedge
• screw
• Lever
• Wheel and axle
• pulley
What are some examples
of simple machines?
• Do you know what • Do you use your
a seesaw is?
bare hands for
cracking nuts?
• Have you ever
used a crowbar?
• Why do scissors
cut paper?
• Have you ever
seen a car with a
• How does a bat hit
flat tire jacked up?
a home run?
Levers
in the body
• Most of the machines in your body are levers that
consist of bones and muscles.
• How can you bend your arm?
• Your biceps muscle provides the input force. The
output force lifts your arm.
• How can you tilt your head back?
• The joint at the top of your neck is the fulcrum of
a first class lever. The muscles in the back of
your neck provide the input force.
Point your left index finger
(your pointing finger) in front
of you. Then move it to the
right.
• Where is the
fulcrum?
• Where is the input
force?
• What kind of lever
is your finger?
How do you find
mechanical advantage?
• The diagram of the
simple pulley shows
how the effort rope and
object move.
• The distance moved by
the effort rope divided
by the distance moved
by the object.
• 60 cm  20 cm = 3
Effort
force
60 cm
Output
force
Load
20 cm
How do you determine the
amount of force necessary to lift
objects with a pulley?
Effort
• Pulley systems can be
very helpful in lifting
heavy loads with a small
effort force.
• As the mechanical
Output
advantage increases, the force
effort force required to 300 N
lift a load decreases.
Load
• 300 N  100 N = 3
force
100 N