Today, we learned math and read the secret of odometer. At lunch, I asked my mother, "Mom, mom, where is the odometer in our car?" Pulling my mother to the front of the car, my mother pointed to the dashboard of the cab and said, "This dial is the odometer and mileage display dial."

In the afternoon, my mother took me to my aunt's house. I just got on the bus. My mother asked me, do you know how many kilometers we have to walk to get to my aunt's house? I said, "I don't know now. I didn't know until menstruation's house. " Before I left, I looked at the number on the odometer and said, "I don't know." My mother told me that now look at the mileage of the odometer, 45,000 kilometers, and we will know when we get to menstruation's house.

When I arrived at menstruation's house, I looked at the odometer 450 16 km in a hurry. I secretly calculated 45016-45000 =16 (km). I'm glad to tell my mother that it's 16 kilometers from our home to menstruation's. My mother praised me, and I was very happy. I only knew before that menstruation's house was not far away, and my mother took me there for a while. Today, I learned the odometer, which let me know how far it is. I will study harder and learn more knowledge in the future.

Expand knowledge:

Mileage may not be accurate.

The mileage displayed on the dashboard is not necessarily accurate, and the biggest variable comes from the diameter of the tire. When designing a car, the mileage is calculated according to the theoretical diameter of the tire. However, in the actual use of automobiles, tires are often compressed, and the actual diameter is smaller than the theoretical diameter. In addition, tire wear, the level of tire pressure and the change of tire model will all affect the mileage calculation.

There is an interesting question, that is, will it be several kilometers when reversing? The fact is that it doesn't matter whether the odometer goes forward or backward. Because the odometer signal is electromagnetic induction, no matter how the wheel rotates, as long as the magnetic field lines are cut, it will send a signal to the driving computer as the counting basis of the odometer.