Step 1: Pick a Topic
Force and Motion: Levers
Step 2: Research
• Stop Faking It! Energy, by William C. Robertson
Step 3: Question
Where should the fulcrum be placed to require the least amount of force
to lift a 50 g load?
Step 3: Variables
Manipulated Variable: Placement of fulcrum
Responding Variable: N of force or number of grams to move load
• Same cup on each end
• Same Wooden Ruler and pen (as the fulcrum)
• Same amount of load (50 g)
• Newtons or grams measured when ruler is touching the table
• Same amount of tape holding the cup to the ruler
Step 4: Hypothesis WITH Research
I think the fulcrum placed the closest to the ruler will take less newtons
of force or grams, to lift a 50 g load. I think this because I’ve found,
through research, that a fulcrum is part of a lever in a simple machine.
A lever makes work easier and uses less energy or requires less force to
lift a load. I have also noticed that people use levers to help them
complete daily tasks.
Step 5: Materials List
Wooden Ruler 12 inches (30 cm)
1 or 2 Plastic Bathroom Cups 3oz (88.7 mL)
Ink Pen with cap
50 g weight
Push Pull Spring Scale or Metal Washers for gram weights
Step 6: What’s the Plan?
2. Details of testing – see variables
3. Measurable results newtons and/or grams
5. Repeat test – 3 trials
Step 7: Procedure
1. Build Lever
a. Use 5 cm of masking tape rolled under each cup.
b. If using metal washer to measure grams, place each cup at
the end of the ruler.
c. If using the push pull spring scale to measure, only use one
d. Put a 50g piece in one cup at the 0 cm end, this is the load.
2. Place the fulcrum, pen, at the 21 cm mark on the lever. Hold pen
in place with one hand.
3. Measuring Force:
a. Use the push end of the push pull spring scale to push down
on the rulers end until the ruler touches the table.
b. Place gram pieces into the cup until the ruler touches the
4. Record results, and repeat two more times for three trials.
5. Repeat procedure with fulcrum, pen, at 15 cm and 8 cm marks on
Step 8: Data
Fulcrum Trial 1 Trial 2 Trial 3
21 cm 1.5N / 150g 1.5N / 150g 1.5N / 150g
15 cm .5N / 50g .5N / 50g .5N / 50g
8 cm .1N /10g .1N / 10g .1N / 10g
Step 9: Discussion of Results/Charts & Graphs/Pictures
Setting the fulcrum at 8 cm, which was closest to the load, took the
least amount of effort or grams to lift the load. The lever produced a
force of .1N/10g to lift the load of 50 g. When the fulcrum was set at 15
cm, it took .5N/50g of force to lift the 50 g load. The measurement
furthest from the load produced the most amount of effort with
1.5N/150g of force to lift a 50 g load.
Step 10: Conclusion
My hypothesis was that the fulcrum placed closest to the load on the beam
will take the least amount of newtons or grams, to lift the load. The
results indicate my hypothesis should be accepted. The fulcrum placed closest to
the load, 8 cm, took the least amount of effort to move a 50 g load.
This experiment proved that the easiest way to move a load with a lever is to place
the fulcrum close to the load. When the fulcrum was places at 8 cm, it only took a
force of .1N/10g. As the fulcrum moves further from the load, more force is
required to lift the load. At 15 cm it took .5N/50g to lift the load, and at 21 cm it
took even more effort by using the 1.l5N/150g of force.
Even though I was correct in my hypothesis, I was surprised how little force it took
to lift a load of 50 g. I learned that when the fulcrum is placed in the middle, the
work done on the system is equal to the work done by the system. That is why it
took .5N/50g of force to move a 50g load. Through further research I also learned
that each time you change the position of the fulcrum you change the load’s
gravitational potential energy by raising the load up. This means that the effort
arm distance is also changing. So, when moving the fulcrum closer and farther
away from the middle there is a difference in the distance you have to push down
on the effort arm end, which means the load arm requires different amounts of
effort. When the fulcrum is close to the load, the effort arm has a greater distance
to move and the load arm has less of a distance to move. Where the fulcrum is
farther away from the load, the effort arm has a smaller distance and the load arm
has to move the load a further distance. See chart below.
Fulcrum Load Arm Effort Arm
8 cm 1 cm 3.3 cm
15 cm 1.9 cm 1.9 cm
21 cm 2.6 cm 1.2 cm
I have learned that people use fulcrums everywhere is their daily lives to make
work easier. Just in preparing my science project I used scissors and a stapler
which are both levers. Both simple machines make work easier by using less
energy to do work.
Because of the results of this experiment, I wonder if changing the thickness of the
fulcrum would have made a difference in the results. This would be a very
interesting variable to change and see if there is a difference in the results.
Step 11: Abstract
People are always looking for an easier way to do work, and I am no
different! Through simple machines, people around the world and for
thousands of years have been using levers to do their work with less
effort. My interest in this topic started while studying force and motion
and thinking about the amount of energy or force used to move objects.
While thinking about this problem I came up with my hypothesis: I
think the fulcrum placed closest to the load will take less newtons of
force or grams, to lift the load. I think this because I’ve found, through
research, that a fulcrum is part of a lever in a simple machine that can
make work easier. Levers use less energy or require less force to lift a
load when the fulcrum is placed closest to the load on the beam.
Through this experiment I wanted to see if the fulcrum placement made
a difference in the amount of effort it took me to lift a load. When I
devised my plan, I tried to make sure all my variables were controlled.
I used the same ruler, cup, pen, spring scale, and load amount. The
only variable I manipulated was the placement of the fulcrum.
My final results showed that the easiest way to lift a load with a lever is
to place the fulcrum close to the load. When the fulcrum was placed at
8 cm, it only took a force of .1N/10g. As the fulcrum moves further from
the load the more effort is required to lift the load. At 15 cm it took .5N/
50g to lift the load, and at 21 cm it took even more effort by using the
1.l5N/150g of force.
In conclusion, I have proven that my hypothesis was correct: the
fulcrum placed closest to the load, at 8 cm, took the least amount of
effort to lift a 50 g load. The most important thing I learned is little
force is needed when lifting a heavy load, when the fulcrum is placed
close to the load.