Can foam plate under electronic scale add weight?

The experimental results showed no weight gain

The author of the post said that he bought 900 grams of snow pear in a booth in Jinshan District, and found that the electronic scale was padded with foam board, and then the fair scale was reweighed, which was 100 grams less! To this end, the reporter visited the Meizhou market in the petrochemical street of Jinshan District and found that most vendors would pad foam under the electronic scale. Gu Zhongming, the chief staff member of the metrology department of Jinshan District Quality Supervision Bureau who has been engaged in metrology for many years, believes that the foam board should be padded for waterproofing and moisture-proof, rather than weight gain. He got two pieces of foam with different thickness and a 500g weight to do the experiment. First, he put an electronic scale on the platform and put a 500g weight on it. The display was correct. Later, he put a 10cm thick foam board and a 3cm thin foam board under the electronic scale, and the screen still showed 500g after weighing.

The post theory is somewhat one-sided

The post said that padding foam can cheat, which is to quote a physics teacher's point of view: foam and cardboard are padded under the scale, which will lead to deformation and buffering, resulting in upward acceleration, which will lead to the support force of the tray to the object greater than the gravity of the object, resulting in overweight, so the pointer reading of the scale is too large.

Is this statement accurate? The reporter consulted Yan Zhendao, the leader of the physics discipline in Hongkou District and a senior teacher at Shanghai Beijiao Senior High School. Mr. Yan said that the above interpretation method is generally correct, but also one-sided. "From the physical point of view, when the electronic scale is placed on foam board or cardboard, it will be weightless in an instant, and the reading will be slightly smaller than the actual weight, but it will rebound" overweight "immediately, and the reading will be larger, and then it will return to normal soon. The whole process only takes a few seconds." This is consistent with the experiment of the Quality Supervision Bureau. The quality supervision department stated that the correct weighing indication should be read after the "stability indicator light" of the electronic scale is on.

Be wary of other cheating methods

How did the poster's' lack of scale 'occur? According to the quality supervision department, there are many cheating techniques for electronic scales nowadays, ranging from traditional methods such as pulling ropes, sticking black tape, and button cheating, to recent methods such as installing remote controls and chips. Gu Zhongming demonstrated to reporters that on an ordinary electronic scale, a 500g weight is placed, but when the button hidden under the button is pressed, the displayed weight immediately becomes 550g. Another example is chip password cheating, where vendors can set passwords arbitrarily. Gu Zhongming demonstrates: Place a 500g weight, press the M1 key, 500g becomes 550g, and press the M2 key to increase the weight to 600g

In order to protect the legitimate rights and interests of consumers, the Shanghai Municipal Bureau of Quality and Technical Supervision has taken multiple measures in recent years, setting up "self-service fair scale convenience devices" near stalls such as live seafood, seafood, and poultry. Currently, they have covered most standardized markets in the city. The quality supervision department suggests that consumers can use their personal belongings (such as mobile phones or keychains, weighed on a safety scale in advance) to compare on the booth electronic scale when weighing; You can also go to the self-service fair scale or fair scale for re weighing. In case of disputes, complaints can be reported to the quality supervision department or market supervision department. For vendors confirmed to have engaged in illegal cheating, in addition to confiscating measuring instruments and illegal income according to the Measurement Law, administrative penalties of up to 2000 yuan may also be imposed.