Poppin Pink Projectiles

Holly Fires Off a Round

When setting up forms for the concrete pour of the structural walls we put up a lot of insulation around the reefer. Some of the threaded steel rods were already mounted in the retaining wall. To put the 2″ pink foam on we popped it onto the wall and rods. The steel rods pushed out little divots of foam at high speed.

Ben caught this succession of three images using the video mode of our camera. The green arrow shows the position of the pink projectile in three consecutive frames 1/29.97th of a second apart. Later I put a tape measure up against Holly to measure the distances traveled. It appears that the missiles shoot out at about 22 mph initially but are already decelerating by the time they pass her shoulder. That’s about 32 feet per second or 1,920 feet per minute.

Looking at the second frame delta d it can be seen that the large air resistance of the projectile has already slowed it down to about 17 mph. The cone is traveling backwards and has little mass yet a large surface area so it is slowing rapidly.

Great homeschool fun on the construction site.

Outdoors: 25째F/19째F Partially Sunny
Tiny Cottage: 68째F/61째F

About Walter Jeffries

Tinker, Tailor...
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2 Responses to Poppin Pink Projectiles

  1. Anonymous says:

    Cool little science project! You make schoolwork fun!

  2. Eve says:

    Love the home school side of construction. Learning does not have to be dry rote sitting on your but in the class room bored out of your mind. Good job and thanks for the inspiration!

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