# AP Physics Lab 7 Lauren Scull Linnea Segen Weight by sparkunder21

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```									                                           AP Physics Lab 7
Lauren Scull & Linnea Segen
Weight Room Force Lab
10/23/06

Purpose: The purpose of this week's lab is to investigate the difference between a work out device
using a pulley with two cables pulling up on the weights versus one that has only a single cable pulling
up on the masses.

Procedure:

- Tricep Pull-Down

- First, we set up the force probe under Ben's feet.

- Ben lifted various masses using the Tricep Extension's 2-pulley system.

- We zeroed the force probe when Ben was just standing on it and recorded the force Ben applied
when lifting a mass.

- The force probe measured the force Ben applied to lift the masses. (The force applied is found by
finding the difference in force between the detected force when Ben is lifting nothing and the detected
force when Ben is lifting the mass.)

- Lat Pull-Down
- First, we set up the force probe under Ben's feet.

- Ben lifted various masses using the Lat Pull-Down's 1-pulley system.

- We zeroed the force probe when Ben was just standing on it and recorded the force Ben applied
when lifting a mass.

- The force probe measured the force Ben applied to lift the masses. (The force applied is found by
finding the difference in force between the detected force when Ben is lifting nothing and the detected
force when Ben is lifting the mass.)

- Final Steps

- Use the number on the weight as the amount of mass (in pounds) and calculate the force gravity.

- Find the force applied by analyzing the graphs we recorded and saved during our trials.

- Graph Force Gravity vs. Force Applied and analyze.

Data:
- Tricep Pull-Down
Force Applied Force Gravity
# on weight
(N)            (N)

30             57.49           133.5

50             98.52           222.5

70             157.2           311.5

90             185.8           400.5

110             231.2           489.5

130             271.1           578.5

150             316.4           667.5

170             362.1           756.5

190             395.9           845.5

200             420.4            890

- Lat Pull down

# on weight      Force Applied (N) Force Gravity (N)
10                   13.56           44.5
20                   51.94              89
30                   98.46           133.5
40                   141.2           178
50                   181.3           222.5
60                   216.3           267
70                   463.8           311.5
80                   303.1           356
90                   346.1           400.5
100                   387.1           445
Conclusion:
In Lab 7: the weight room force lab, we investigated the difference between a workout device using
a pulley with two cables pulling up on the weights and one that has only a single cable pulling up on the
masses. For the Tricep Pull-Down, we set up the force probe under Ben's feet. Then, Ben lifted various
masses using the Tricep Extension's 2-pulley system. Next, we zeroed the force probe when Ben was
just standing on it and recorded the force Ben applied when lifting a mass. The force probe measured
the force Ben applied to lift the masses. (The force applied is found by finding the difference in force
between the detected force when Ben is lifting nothing and the detected force when Ben is lifting the
mass.) We followed the same procedure for the Lat Pull-Down's 1-pulley system. For our final steps,
we found the force gravity pulling down on the weights during each trial and analyzed the graphs to find
the force applied in each trial.

After graphing our results, we linear fit our graph. We found that for the Tricep Pull-Down's 2-pulley
system, the Force Applied was about half of the Force Gravity. The slope of the graph was .4764
(about .5 which is what it should have been). We also found that for the Lat Pull-Down's 1-pulley
system, the Force Applied was about the same as the Force Gravity. The slope of the graph was .936
(about 1 which is what it should have been). These results show us that when using the two pulley
system, we are only lifting half of the weight while when we're using the 1-pulley system we're lifting
the entire weight.

For this experiment, we only pinpointed one significant source of error. During some of the trials, it
appeared as if Ben was not pulling completely downward. He may have been pulling slightly to either
side. This would have affected our Force Applied data and in turn would have affected the slope of our
graphs. This is probably why our graphs did not have the exact slope they should have. We could have
fixed this problem by making sure that Ben was pulling directly down. Another less problematic source
of error was zeroing of the force probe. After zeroing it, the force probe seems to change slightly before
Ben even holds on to the weights, which suggests that other factors are preventing the probe from
measuring only the force applied. By conducting the lab in a controlled environment where all forces
can be accounted for, we can determine how much of the force is a result of Ben pulling on the weights.

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