Ballistic Pendulum
Project
By: Blake Reser, Tyler Snyder, Libby Banse-Fay, Nick Hines, Robbie Ellis, Robbie Price
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Background
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Statement of problem
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Hypothesis
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Diagram
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Supplies
Physics Research Paper
Background:
To conduct an experiment that uses paintball guns to measure the velocity at which a paintball travels, there are many things to consider, evaluate, and calculate. The first step in the process is identifying the type of paintball guns. The two types that will be used for the experiment are a Tippmann 98 Custom and a Spyder Xtra. The Tippmann 98 Custom is a used gun, while the Spyder Xtra is a new gun. This is important to note because the Tippmann 98 paintball gun, could be functioning at a lower level, as compared to a new gun.
A paintball gun is a weapon designed to simulate an actual gun in a war simulation, while paintballs are easily identifiable when checking if a target was hit. A paintball gun works by releasing compressed air and causing propulsion upon the paintball firing it. The gas is usually Carbon Dioxide, while it could be pumped air. When the gas is released, it flows up the tube into the barrel, where it fires the projectile at a high rate of speed.
Moving on, the next thing to consider is the ammunition that will be used, which is Inertia Paintballs. Each individual paintball is 0.68 Caliber and this will be kept constant throughout the experiment. Another aspect is testing the velocity in relation to the state of the paintball. Also, there will always be air friction, which is what causes the paintball to slow down, as well as gravity. In addition to air friction and gravity, we will ultimately be measuring how temperature affects the velocity of a paintball. We will be using three varying temperatures; a frozen state at 15 degrees Fahrenheit, a normal state of 60 degrees Fahrenheit, and a temperature of 30 degrees Fahrenheit.
To measure the velocity of a paintball we are going to use a ballistic pendulum. The ballistic pendulum is a device that is used to measure the velocity of an object by retaining the bullet upon impact, and its velocity is a function of the displacement of the pendulum.
We are going to use the formulas: (2gh)^(½) = V & (m+m)V=mV. The “g” in the first equation stands for gravity, which is equal to 9.81 m/s squared. As for the “h”, it represents the change in the height of the pendulum when it is hit by the paintball. Finally, the V is the velocity of the pendulum and paintball, which can be substituted into the second equation. For the second equation, the first “m” represents the mass of the paintball, and the second “m” represents the mass of the pendulum. As for the first “V”, it represents the velocity of the pendulum and paintball, which we can find by using the first equation. After the equal sign, the next “m” signifies the mass of the paintball. Finally, the last “V” stands for the Velocity of the paintball and the variable we are trying to find.
It has been shown that the temperature of a projectile can greatly affect the speed it travels. The paint ball will condense at a frozen temperature, while it will expand when heated to a hotter temperature. Not only does the condensing and expansion of the projectile increase mass, we believe that it will increase/decrease velocity. Overall, the paintball experiment will be very exciting and informative, and also provide us with a better understanding of velocity and air friction.
Statement of the Problem:
The purpose of this problem is to find the velocity of a paintball, shot by a paintball gun, in different physical states: 15, 30, and 60 degrees Fahrenheit.
Hypothesis:
We believe that the paintball is going to have a faster acceleration when it is in a colder temperature compared to a higher temperature. We believe this because the paintball will have less resistance when it is slicing through the air. Also, we believe that the frozen paintballs will withstand air resistance much more effectively than the warmer paintballs. Aerodynamics plays a big role in determining how fast an object travels.
We are going to measure the temperature of the paintball by using a temperature gun. As for the velocity of the paintball, we are going to make a ballistic pendulum and use mathematical equations to calculate the velocity. The controlled variables in the experiment include the two paintball guns, the type of paintballs, the target, distance, and the CO2. The dependent variable in the experiment is the velocity that we are going to calculate. Finally, the independent variable is the three different temperatures of the paintball. The temperatures we are going to use are 15, 30, and 60 degrees Fahrenheit.
The set up of the experiment was quite simple and remained constant throughout the entire procedure. The first thing we had to do for this experiment was to set up a table to attach the ballistic pendulum. We began by making a table with two sawhorses and a sheet of plywood. Then we built a ballistic pendulum that would swing when it was hit by a paintball. The ballistic pendulum was made out of lightweight sheet metal and rivets. The sheet of metal was connected to two hinges on either side that produced little to no resistance on the sheet. The sheet of metal hung off the side of a table at a 90 degree angle, forming what is known as a ballistic pendulum. After the ballistic pendulum was set up, we placed a 45 pound weight on the plywood so it would remain steady and not shift when the paintball would strike the ballistic pendulum. Fifteen feet from our ballistic pendulum, a stand was aligned where the paintballs would be fired from both of the paintball guns. Next to the pendulum stood a shovel embedded in the ground that stood in a perfect line, with a ruler taped onto it at the same level as the pendulum. A couple feet away from the shovel, a camera was placed to capture the movement of the pendulum after it was struck by the paintball. For each gun, three trials were conducted. The trials were done for the three states in which the paintballs were in. Ten shots were fired in each trial. So altogether, there were six trials and sixty data points gathered. Before the paintballs were shot, we used the temperature gun to ensure that they were the precise temperature we wanted. Also, keeping the distance the same was an imperative factor in order to find the exact velocity for each shot fired and obtain accurate data.
Diagram:
Supplies:
● Spyder Xtra gun
● Tippmann 98 Custom gun
● Paintballs
● CO2
● Ballistic Pendulum (sheet metal, two hinges, and arms to attach to table)
● Screws (to stabilize gun to table)
● Table (two sawhorses and a sheet of plywood)
● Measuring Tape
● Temperature Gun
● Ruler
● High Definition Camera
● Tripod for Camera
● Stand or Clamp (to stabilize gun)
● Towels
● Screw Driver
● Cleaning supplies for the Paintball Guns
The results told us that the 30 degree Fahrenheit paintballs had a faster velocity than at the temperatures of 15 and 60 degrees Fahrenheit. This was true for the Tippmann 98 Custom and the Spyder Xtra paintball guns. All three temperatures had a significant amount of variance, but the averages made it clear that the 30 degree Fahrenheit paintballs were the fastest.
Average Velocities:
15º = 133.51 mps
30º = 149.86 mps
60º = 120.09 mps
Average velocities:
15º = 107.81 mps
30º = 119.24 mps
60º = 95.59 mps