The traffic police on duty on the Jingchang Expressway stopped a speeding car. After saluting the driver, the traffic police said, "your speed exceeds the limit of 120 km / h". Before the traffic police finished, a child in the car said, "we only drove for a few minutes, and we didn't have to wait If you are the traffic policeman, how can you explain to the children?

The traffic police on duty on the Jingchang Expressway stopped a speeding car. After saluting the driver, the traffic police said, "your speed exceeds the limit of 120 km / h". Before the traffic police finished, a child in the car said, "we only drove for a few minutes, and we didn't have to wait If you are the traffic policeman, how can you explain to the children?

A: because the child doesn't understand the physical meaning of speed, 120 km / h refers to the speed of the car, that is, the distance of the car per hour is 120 km, not a few minutes; the average speed of the speeding car in a few minutes exceeds the prescribed speed of 120 km / h, so he is fined

Ask a question to fill in the blanks about physical movement and force in grade two of junior high school
When two drops of mercury are close to each other, they can automatically combine to form a larger drop of mercury. This fact shows that there is - between molecules. Using the needle tube to draw half a tube of water, pressing the needle nozzle with the index finger, and then pushing the piston hard, it is found that the water - is compressed, indicating that there is - between molecules——
My classmates talk about gravitation, difficulty and repulsion; others talk about gap, difficulty and gap

How are you
Gravity
Not easy.
repulsion.
In fact, all can be eight, see your exercise book out of the problem is for which part of the learn to fill in according to that part