Several methods for adding balance weights

After adjusting the balance according to the correct steps, it is important to quickly weigh the object and master the method of quickly adding weightsHow to add weights to a balance correctly and quickly?Shanghai Zhongyuan believes that the following three rules should be followed:

1. First increase the weight in sequence, then add the smaller weight. After each weight addition, pay attention to observing the balance of the balance;

2. When a weight is added and its mass exceeds the mass of the object, it should be immediately removed, and the removed weight should not be added to the plate again;

3. When continuing to add smaller weights, pay attention to the relationship between the mass of several smaller weights and the mass of the weights that have already been removed. If the mass of a small weight and several small weights on the plate is equal to the mass of the weight that has already been returned, this small weight should not be added to the plate

For example, a certain balance has two sets of weights besides the floating weight, of which 9 are in grams: 1, 2, 2, 5, 10, 20, 20, 50, and 100; There are 8 units in milligrams: 10, 20, 20, 50, 100, 200, 200, 500. This balance is used to weigh the mass of an aluminum block. The actual process of adding weights is completed according to the following 5 steps. Please read the mass of the aluminum block

(1) First add a 100 gram weight, then add a 50 gram weight. If the weight exceeds the limit, remove the 50 gram weight

(2) Add a 20 gram weight, the weight is not enough, add another 20 gram weight, the weight is still not enough, add another 5 grams of weight, the weight is still not enough, add another 2 grams of weight. If the weight is found to be overweight, remove the 2 grams of weight

(3) Adding an additional 11 grams of weight, it was found that the weight was not sufficient. Adding an additional 500 milligrams of weight, the weight was still insufficient. Adding an additional 200 milligrams of weight, it was found that the weight was overweight. The 200 milligrams of weight was removed

(4) Add another 100 milligrams of weight, and if the weight is still overweight, remove the 100 milligrams of weight

(5) Continuously add 50 milligrams and two 20 milligrams weights. If the weight is still not enough, then move the weight to the 4 milligrams position and the balance will be perfectly balanced

So, the mass of the aluminum block was measured to be 146 and 594 grams

In step (2) of adding weights, after adding a second 20 gram weight, it was found that the weight was still not enough. Why not add a 10 gram weight and directly add a 5 gram weight? The reason is that if a 10 gram weight is added to the plate, the sum of its mass and the two existing 20 gram weights on the plate is 50 grams, which is equivalent to adding the previously removed 50 gram weight back to the plate. Similarly, in step (5) of adding weights, after adding two 20 milligram weights, it is found that the weight mass is still insufficient. If another 10 milligram weight is added, the total mass of it, two 20 milligram weights, and one 50 milligram weight is 100 milligrams, which is equivalent to adding the previously removed 100 milligram weight back to the plate

It can be seen that by paying attention to the relationship between several smaller weights and the larger weights that have already been removed, it is possible to avoid unnecessary weight additions. Therefore, it is an important step in quickly weighing an object with a balance