（213? Liaocheng) As shown in the figure, a solid cylinder is hung under the spring dynamometer, and the cylinder is slowed from the top of the container containing water to a certain height from the w

（213? Liaocheng) As shown in the figure, a solid cylinder is hung under the spring dynamometer, and the cylinder is slowed from the top of the container containing water to a certain height from the water surface. (1) As can be seen from the image, when h=, the indicator of the spring dynamometer is 12N, and the cylinder is in the air at this time. According to the two-force balance condition, G=F = 12n;

(2) In the image, the CD segment is the case that the cylinder is completely immersed in water. At this time, the pulling force on the cylinder is F=4N,

then the buoyancy force on the cylinder is f G=mg-f = 12n-4n = 8n.

(3) When the cylinder is completely immersed in water, it is ranked according to f = ρ water gV:

V =V row = F. g=12N? 1N/kg=1.2kg,

then the cylinder density ρ =mV =1.2kg8×1? 4m3 = 1.5× 13kg/m3.

(4) It can be seen from the image that the depth of the lower surface is h=4cm=.4m, regardless of the rise of the water surface, when the cylinder is just submerged and the object descends by 4cm.

therefore, the liquid pressure on the lower surface just after immersion is P=ρ water GH = 1.× 13kg/m3× 1n/kg× .4m = 4Pa．.

Answer: (1) The gravity of the cylinder is 12n.

(2) The buoyancy of the cylinder when submerged is 8n.

(3).