2007-03-02 03:48:52 · 4 answers · asked by RDubs 2 in Science & Mathematics ➔ Zoology
the more accurate answer is that the pressure on the outside of the index card is greater than the pressure on the inside I point this out because you can not truly suck air it is really a difference in pressure between two areas. so basically the system ( the class) has reached a state of equilibrium where the pressure on the out side is high enough to keep the card in place and it will stay so until energy is added to the system.
2007-03-02 06:16:51 · answer #1 · answered by Cody B 1 · 0⤊ 0⤋
The index card prevents air from trading places with the water and creates suction.
2007-03-02 04:01:36 · answer #2 · answered by Barbados Chick 4 · 0⤊ 0⤋
Due to upward pressure of the air.
2007-03-02 11:21:07 · answer #3 · answered by moosa 5 · 0⤊ 0⤋
surface tension and the cohesive force of water molecules
2007-03-02 05:33:06 · answer #4 · answered by Bio-student Again(aka nursegirl) 4 · 0⤊ 0⤋