1. Work, Power and
Simple Machines

2. Machines Make work easier to do by:
Increasing the size of an applied force
Changing the direction of an applied force
Changing the distance over which a force acts
There will always be a trade-off!!!

3. Sketch, label, and describe each
different method.
Challenge:
Create three machines to lift the mass in three different ways
Use the following materials:
Ruler
Marker
tape

4. The Six Simple Machines
pulley
lever
inclined
plane
screw
wheel &
axle
wedge

5. Some machine basics… Input output
What goes in…
Output is also called “resistance:”
Resistance force is the force exerted by a machine
Resistance distance is the distance across which the machine applies effort
Input is also called “effort:”
Effort force is the force applied to a machine
Effort distance is the distance across which the effort is applied
output
What comes out…

6. Levers LOAD EFFORT FULCRUM The mass being lifted by a lever
Force used to
lift the load
FULCRUM
Fixed point about which
the lever rotates
Review: Force is a push or a pull on an object, and is measured in Newtons

7. 1st Class Lever RESISTANCE DISTANCE… EFFORT DISTANCE… FULCRUM…
is between the effort and the load

8. Your experiment… Use the following materials: Ruler Marker Tape
Explore the relationship between effort force required to lift a load, and the length of the resistance distance.
Use the following materials:
Ruler
Marker
Tape
Spring Scale
100-g mass
Resistance Force = ____ N

9. Your experiment… Data Collection:
- repeat for 3 trials at this fulcrum position for consistency
- average the effort needed for this fulcrum position
Data Table 1: Effort force measurements for fulcrum positioned at ____ cm
Trial
Fulcrum Position (cm)
Resistance Distance(cm)
Effort Force (N) 1 2 3
Average

10. Ideal Mechanical Advantage Actual Mechanical Advantage
Number of times the input is increased by a machine
Ideal Mechanical Advantage
The mechanical advantage in a “perfect” world; predicted mechanical advantage
Actual Mechanical Advantage
The real mechanical advantage that results when the machine is in use

11. Summarize your findings
What did you determine, through your experiment, about the relationship between the (length of the) resistance arm and the effort needed to lift the load?