(1) Measure the gravity g of iron.

(2) measure the gravity of the empty g bucket.

③ When the iron block is submerged in the water, read the indicator F of the spring dynamometer.

(4) Measure the total gravity g of the bucket and water.

So the answer is:

(2) According to the measurement data in (1), the table is designed as follows:

So the answer is:

Gravity of iron block G/N gravity of empty bucket g bucket /N indicator of spring dynamometer when iron block is submerged in water F/N total gravity of bucket and water g total /N? ? ? ? (3) Calculate the buoyancy and gravity of boiling water according to the data in steps (1) and (2),

Buoyancy is equal to the gravity g of the iron block MINUS the indicator f of the spring dynamometer when the iron block is immersed in water, that is, f float = g-f;

The gravity G row of boiling water is equal to the total gravity G of the bucket and water minus the gravity G of the empty bucket, that is, G row =G total -G bucket;

Compare the size relationship between F float and G row.