① Fix the spring and scale, and record the position of the end of the spring;

(2) Hang the bucket on the spring, and measure the elongation of the spring △l0 with a scale, as shown in figure1;

③ In the Middle Ages, the barrel was filled with water, and the elongation of the spring was measured with the scale △l 1, as shown in Figure 2;

④ When the bucket is full of drinks, measure the elongation of the spring △l2 with a ruler, as shown in Figure 3;

(2) The elongation of the spring is in direct proportion to the tension it receives,

Then △ l0△ L1= f0f1= G0G0+G water =G0G0+ρ water gV,

△l0△l2=F0F2=G0G0+G beverage =G0G0+ρ beverage gV,

Solution: ρ beverage =△l2? △l0△l 1？ △l0ρ water;