Air+Pressure+Lab

Problem: Do you think it is possible to keep water in an upside down cup using only a piece of paper?

Hypothesis: I dont think the paper will stay because water can leak through paper very easily. I think the water will all spill.

Experiment: The materials we needed were a small plastic drinking cup, a small basin, an index card, a pushpin, and a piece of tape. 1.Fill a small drinking cup to the top rim with water and place the index card on top of the cup. Hold the cup over a basin or sink. CAREFULLY turn the cup upside down while holding the card firmly in place. Then release your hand from the card while still holding the cup.

2.Try the activity again, but first use a pushpin to poke a small hole in the bottom of the cup. Cover the hole with tape, and then repeat step one. While the cup is upside down, remove the tape from the bottom of the cup.

Observation: We put water in the cup and put the index card on top and slowly tipped the cup over. The water stayed in the cup because of the air pressure on the outside of the cup was trying to get in the cup and pushed the index card close to the cup so the water wouldnt come out. Next we put a hole in the top of the cup with a pushpin. All of the air pressure on the outside of the cup came in the hole and all of the water came crashing out at once. So the answer to the question is yes, the water will stay in the cup.

Conclusion: After filling the cup with water, putting an index card on it, and turned it over I found that the water did not spill because the air pressure on the outside was pushing on the index card and keeping it from falling. When we put a hole in the cup the water all spilled out at once with the index card. What happened was the air pressure on the outside of the cup seeped in through the whole and the air pressure was no longer on the index card. The air pressure on the inside of the cup was greater than the air pressure on the outside.