Download the study of if straws of different lengths

THE STUDY OF IF STRAWS OF DIFFERENT LENGTHS EFFECT THE DISTANCE A SPITBALL
FLIES
Ethan Wilk
Cary Academy
ABSTRACT
The purpose of this study was to find what combination of size of straw, place in straw, material, and
liquid that the spitball is dipped in that shoots a spitball the farthest. The farther back the spitball
made out of paper towels were pushed into the straw the farther the spitball flew, this is because the
farther back in the straw you push the spitball the more pressure build up and acceleration there is
making the spitball go out of the straw with more speed and force. The method used was to change
the independent variable (size of straw, material, etc.) then load the spitball into the straw and shoot
it, the point where the spitball stops moving is measured with meter sticks. The overall farthest flying
spitball was a two square cm piece of paper towel dipped in water rolled into a ball and shot from the
tip of an eighteen cm long straw. The results are this way because paper towels absorb water the
best weighing it down and making it more aerodynamic.
INTRODUCTION
A water gun is a toy gun designed to shoot streams of water. To use a water gun one would pull the
trigger back pushing the piston into the cylinder. The piston compresses the spring causing the spring
to push the piston back out of the cylinder when you release the trigger. These 2 strokes of the piston
into the cylinder and out again constitute the entire pump cycle.
“Projectile motion is a form of motion where a particle (called a projectile) is thrown obliquely near the
earth's surface, & it moves along a curved path under the action of gravity. The path followed by a
projectile motion is called its trajectory. Projectile motion only occurs when there is one force applied
at the beginning of the trajectory after which there is no interference apart from gravity”.
Figure 1: Air blown into a straw builds up pressure which reaches a certain point. When it
reaches a certain point it blows away the obstruction.
Air pressure is the weight of the Earth's atmosphere pressing down on everything on the surface.
Atmospheric pressure: the pressure exerted by the atmosphere. When most people think of Air
pressure they think of car tires, basketballs, and balloons, inflatable things that may explode if too
much air is pumped in them.
“Acceleration is when something in physics, a is the rate at which the velocity of a body changes with
time. In general, velocity and acceleration are vector quantities, with magnitude and direction, though
in many cases only magnitude is considered (sometimes with negative values for deceleration).
Acceleration is accompanied by a force, as described by Newton's Second Law; the force, as a
vector, is the product of the mass of the object being accelerated and the acceleration (vector).
The SI unit of acceleration is the meter per second squared (m/s2).
For example, an object such as a car that starts from standstill, then travels in a straight line at
increasing speed, is accelerating in the direction of travel. If the car changes direction at constant
speedometer reading, there is strictly speaking acceleration although it is often not so described;
passengers in the car will experience a force pushing them back into their seats in linear acceleration,
and a sideways force on changing direction. If the speed of the car decreases, it is usual and
meaningful to speak of deceleration; mathematically it is acceleration in the opposite direction to that
of motion”. For example if one dropped a ball and it fell through the air without resistance and it
gained speed that is acceleration.
MATERIALS & METHODS
The materials used in all of the experiments were water, paper towels, straws, honey, milk, printer
paper, rubber, tape, tissues, meter sticks, scissors.
In the first experiment spitballs (2 square cm of paper towel dipped in water then rolled into a ball)
were put in different sections of an 18 cm long straw and then blow out of the straw and the point
where they stopped moving was recorded with a meter stick. The distances the spit balls were shot
from where 18 cm (the tip of the straw), 9 cm (half way down the straw) 4.5 cm (three quarters of the
way down the straw).
In the second experiment different size spitballs (1square cm, 2 square cm, 3 square cm) were shot
from a straw and the point where they stopped moving was recorded with a meter stick.
In the third experiment spitballs were dipped in different liquids (milk, honey, water) and then blown
out of a straw and the distance the spitball flew was recorded with a meter stick.
In the fourth experiment straws were cut into sections (18 cm, 9 cm, 4.5 cm) and then spit balls were
shot out of different length straws and the point that they landed was recorded with a meter stick.
In the fifth experiment different materials (rubber, tape, tissues, paper towels, printer paper) were
made into spitballs (2 square cm of material dipped in water then rolled into a ball) the blown out of a
straw and the point that it stopped moving was recorded with a meter stick.
RESULTS & DISCUSSION
Figure 2: Spitballs shot from different sections of a straw
It was found that the farther one pushed the spitball into the straw the farther distance it flies before it stops (Figure 1).
The spitball shot the farthest (371 cm) when it was pushed three quarters of the way down the straw. When the spitball
is pushed farther back into the straw it has more time to build up speed, momentum and pressure which will make it go
father once it is shot out of the straw.
Figure 3: Different size spitballs were shot from a straw
It was found that 2 square cm spitballs fly farther than 1 or 3 cm squared. This is because if one has a one square cm
spitball it will not be big enough to block enough air to build up enough pressure to push the spitball out of the straw.
Three square cm is too big because it will clog up the straw making the spitball un-moveable. No matter how much
pressure was built up the three cm squared spitball could not be moved.
Figure 4: Spitballs were dipped in different liquids then shot from a straw
Water was found to be the liquid that when a spitball is dipped in it the spitball flies the farthest when shot from a
straw. The water dipped spitball flew 183 cm. Honey was a close second it flew 161 cm. Honey came in second because
although the honey made the spitball heavier and more aerodynamic (by smoothing down all of the random parts
flapping around the ball) it also stuck to the straw slowing it down and it back. Milk came in last, it flew 117 cm. Milk
came in last because the paper towel which the spitball is made out of did not absorb the milk as well as the other
liquids.
Figure 5: Straws were cut into different lengths then had spitballs shot out of them
9 cm long straws were proven to shoot the farthest spitball at a distance of 232 cm. In second came the average (18 cm)
straw shooting a distance of 187 cm. The smallest straw at a length of 4.5 cm shot the spitball 165 cm. The smallest
straw shot the smallest distance because the barrel of the straw could not build up enough air.
Figure 6: Spitballs made of different materials were shot from a straw
The results of this experiment have determined that rubber was the material that when made into a spitball and shot
from a straw it goes the farthest distance which is measured with a meter stick. The distance the rubber spitball flew
was 182 cm. Although rubber went the farthest it was followed very closely by paper towels and then tissues. Paper
towels flew a distance of 173 cm which is only 9 cm away from the rubber spitball 182 cm. The tissue spitball flew a
distance of 157 cm.
CONCLUSION
It was determined that 2 square cm of paper towels dipped in water would make the farthest flying spitball
overall. This information is important because children might want to know how to make the most effective
spitball. The hypothesis that was determined was not correct, Paper towel was thought to be the most
effective material and honey the most effective liquid. In the future it would be interesting to determine
whether swirly straws affect the distance a spitball flies.
CITATIONS
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