My 5th grader has a science project. He chose a water bottle trick.
We know that when you poke a pinhole into a sealed bottle of water the water will not flow because of the lack of air pressure but when you unscrew the cap the water will flow out of the hole.
He is hypothesizing that if you leave the cap on the bottle and also poke a pinhole in the top cap of the bottle that the water will flow out of the pinhole at the bottom of the bottle at a slower rate than if he were to poke 2,3,4 holes in the cap or entirely unscrew the cap because he is letting in only a small amount of air through the top.
He tested this and there was almost no difference in the time it took for the bottle to drain. Why would only a small pinhole in the cap allow the bottle to drain at the same rate as removing the cap entirely?