Saturday, November 25, 2017

Thanksgiving Roll War

As usual, Thanksgiving got a little out of hand in the Cole household. During dinner, my family members somehow forgot how to pass the rolls, and decided the only way to distribute them was to throw them across the room/at whoever asked for one. Being the dedicated physics student I am and as a firm believer in the snowball trick with a very gullible family, I calculated some kinematics of the rolls as they were thrown in the air and across the room.

There were two types of rolls at dinner. The smaller of which had a radius of .035m, and the larger of which had a radius of .05m. My dad gave me a weird look when I told him I had to measure these before he could clean up, but I told him I was just trying to be better prepared for next year.

When my brother throws the first roll during the snowball trick, he shoots it like a basketball so that it rotates. In the 3 he threw in the air as the snowball trick, the rolls averaged about 10 revolutions, and it took about 1 second to reach the target. This is about 62 rad/s. He used the larger rolls, so using wr=v, this gives us a linear velocity of (62rad/s)(.05m)=3.1m/s. The other roll, which he threw directly at my cousin after distracting her with the one he threw in the air, traveled the roughly 2 meters between them in about 0.5s. Using v=d/t, we get a linear velocity for this roll of about 4m/s. The slower moving roll was distracting, so my cousin got hit by the second one, which got there faster because of the higher velocity, despite being thrown second.
The smaller roll, had a smaller radius, but about the same angular velocity when I threw it across the table at my other cousin. Because of the smaller, radius, it had a slower linear velocity, and therefore took even longer to reach my cousin, who was seated about 2 meters from me. Despite my brother’s beliefs, I can throw a roll just as hard as him, so I also threw mine with a velocity of about 4m/s.  This means the smaller roll was an even more effective snowball distraction, because it could distract my cousin longer and give me more time to throw the other roll.

In conclusion, if you are having a roll war at Thanksgiving, hoard all the smaller ones and you will be victorious.

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