The mass of this bottle of pure water is m = ρ V =/kloc-0 /×103kg/m3× 600x10-6m3 = 0.6kg. 。
The weight of this bottle of pure water is: g = mg = 0.6kg× 10n/kg = 6n.
Pressure on sponge when bottle is upright;
F=G=6N，
S=S base = 35cm2 = 35x 10-4m2，
When the bottle is placed upright, the pressure on the sponge is:
p=FS=6N35× 10？ 4m2≈ 17 14.3Pa。
(3) When the back-off device changes, the pressure remains unchanged, and the stress area becomes smaller, which increases the pressure. In order to equalize the pressure, the mass of water can be reduced, thus reducing the pressure:
According to the topic, the stress area of the upright position is 35cm27cm2= 5 times that of the inverted position. To make the pressure equal, the upright position is five times that of the inverted position, so it is required to pour out 45% of the water when standing upside down.
Therefore, the answer is:1714.3 pa; When inverted, pour out 45% water.