Question 13
Phong is a five-year old boy and is going to an elementary school in Hanoi
next year. He is very happy because his family has just had a new car. He wants
to discover the car and wonders how the speedometer works. Phong’s daddy tells
him that the reading from the speedometer shows the speed of the car at that
instant. The speed of the car is proportional to the rate of rotation of the tires.
a. Phong does not really understand how it is possible that the speed of the car is
proportional to the rate of rotation of the tires. Can you clarify that for him?
b. For a car with new tires, the speedometer shows accurately its speed. After a
year or so in using, the tires will wear, and their diameter will reduce an amount
of several millimeters. State and explain the effect, if any, from the reduction to
the reading of the car’s speedometer.
next year. He is very happy because his family has just had a new car. He wants
to discover the car and wonders how the speedometer works. Phong’s daddy tells
him that the reading from the speedometer shows the speed of the car at that
instant. The speed of the car is proportional to the rate of rotation of the tires.
a. Phong does not really understand how it is possible that the speed of the car is
proportional to the rate of rotation of the tires. Can you clarify that for him?
b. For a car with new tires, the speedometer shows accurately its speed. After a
year or so in using, the tires will wear, and their diameter will reduce an amount
of several millimeters. State and explain the effect, if any, from the reduction to
the reading of the car’s speedometer.