Does Resistance Affect The Chance of Winning a Nerf War?

Research

The aim of this experiment is to determine the distance a nerf bullet will shoot based on its change in resistance. This will be completed by removing the original resistors from the gun and soldering wire that has a higher resistance into the circuit, and then taking those out to replace it with resistors that are lower than the original.

The bullets will be shot from the same distance, height, and angle throughout the experiment. All of the bullets are weighted the same, so without any outside variables, they should be in the same range of distance. The velocity of the bullet is directionally proportional to the distance that the bullet travels. If I replace the resistors with a higher or a lower resistance, the question is raised: Will the bullets have a higher velocity with a smaller resistance/Will the bullets go lesser velocity with a higher resistance? Assuming that this is true, I predict that there will be a greater velocity with a smaller resistance, making the data plot linear. My prediction of the graph is pictured below.

Variables

resistance

velocity

-The independent variable is the resistance in the gun-The dependent variable is the distance the bullets go (measured in meters)-The controlled variables include the acceleration of gravity, the height of the apparatus, and the angle the gun is being shot from, the surface the bullets are being shot onto, and the type of bullets being used

Apparatus

-Nerf Rayven-Screwdriver-Non-resistant wire-1.2 ohmic resistance wire (yellow)-0.2 ohmic resistance wire (black)-Wire stripper-Wire cutter-Tape Measure-Meter stick-Soldering Iron-Soldering wire-Camera (to record initial hit of the bullets)

Diagram of Experiment

Method

● Set up apparatus as shown in the diagram.

camerabullet

tape measure

nerf gun

● Set height of nerf gun at 1 meter high. ● Make sure gun is shooting at a 90°. ● Lay a tape measure out for 8 meters at the base of the nerf gun. ● Set camera to record. ● Run an original test without altering the nerf gun at all (resistance of .7 ohms), with 3 bullets of equal weight

being shot 5 times to record data.● Take out original resistors in the gun and increase the resistance by .5 ohms (resistance now 1.2 ohms). ● Repeat test with each bullet being shot 5 times, and record data. ● Take out 1.2 ohm resistors and put in .2 voltage resistors. ● Repeat test with each bullet being shot 5 times, and record data.

This is a picture of the inside of the nerf gun pre-altering it:

This is an image of the nerf gun after altering it:

This is a photo after altering the nerf gun for the second time:

Data

For all three trials, it took an average of 1.8 s for the bullet to hit the ground after being fired out of the nerf gun.

Pre-altered Data (.7 ohms):

Bullet # Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average

#1 6.24 m 6.10 m 7.39 m 5.66 m 6.12 m 6.30 m

#2 6.93 m 6.17 m 6.43 m 6.83 m 6.12 m 6.50 m

#3 6.45 m 6.73 m 6.10 m 5.58 m 5.92 m 6.16 m

The average of all three trials is 6.32 m. Using V=D/t, I was able to calculate the velocity of the non-altered gun. V=D/tD= 6.32 mt= 1.8 s

(6.32)/(1.8)= 3.51 ms-1

V= 3.51 ms-1

Altered Wire of 1.2 ohms:

Bullet # Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average

#1 7.32 m 6.22 m 6.38 m 4.90 m 5.41 m 6.05 m

#2 5.03 m 6.10 m 6.86 m 4.85 m 5.33 m 5.63 m

#3 5.79 m 4.52 m 5.82 m 6.10 m 5.97 m 5.64 m

The average of all three trials is 5.77 m. Using V=D/t, I was able to calculate the velocity of the altered gun. V=D/tD= 5.77 mt= 1.8 s

(5.77)/(1.8)= 3.21 ms-1

V= 3.21 ms-1

Altered Wire of .2 ohms:

Bullet # Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average

#1 6.56 m 6.98 m 6.75 m 7.65 m 6.74 m 6.94 m

#2 7.02 m 7.90 m 6.99 m 7.35 m 7.43 m 7.34 m

#3 7.96 m 6.52 m 7.82 m 6.90 m 7.67 m 7.37 m

The average of all three trials is 7.22 m. Using V=D/t, I was able to calculate the velocity of the altered gun. V=D/tD= 7.22 mt= 1.8 s

(7.22)/(1.8)= 4.01 ms-1

V= 4.01 ms-1

Resistance Uncertainty

The resistance uncertainty can be estimated at around ∓.05 ohms, as I used a fairly old ohmmeter and the number was shifting ever so slightly.

Velocity Uncertainty

The velocity uncertainty stems from the camera used to record the bullet landing. The time when it landed averaged to 1.8, but jumped around ever so slightly. The distance was also very difficult to see from a camera, so I would peg the velocity uncertainty at around ∓.08 ms -1

Graph of Data

Judging by all three velocities with all three resistances, they theoretically should be linear, because the 3 trials all had a difference of .5 ohms.

This graph shows the bullet point at each point and shows its respective uncertainty.

To demonstrate how the graph is fairly linear, I graphed the points with a line of best fit.

The gradient of the average velocities are shown by

Conclusion

In the end, I proved my hypothesis, as the graph is fairly linear. As the resistance grows, the velocity lowers. If outliers were taken out of the equation with Bullet #1 and Bullet #3, the graph would be perfectly linear. As shown by the graph, there is a linear relationship between the velocity and resistance of the gun.

Evaluation

Although I proved my hypothesis to be true, as the graph is linear, there are still many errors that are involved. The gradient of the graph varies by quite a bit, as it shouldn’t vary much at all. This error is mostly due to the velocity uncertainty. It was very hard to determine the exact time and place where each bullet fell.

Other issues were prominent with air resistance, the old ohmmeter, and the different bullets used. There were not many repeated values for distance, which only solidified the uncertainty values.

Improving the Investigation

One improvement would be to use a newer ohmmeter that would give me a more precise value for resistance. It would’ve also helped to have a slow motion camera to better estimate the time and place that the bullets fell. It would’ve also helped to use brand new bullets to guarantee that they were all the same.

Using a bunch of different resistant wires would have also helped find a better line of best fit. Finally, I would have fixed my apparatus to have more than one camera to solidify values to use for velocity.

Grade:personal engagement Exploration Analysis Evaluation Communication Final Score

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