Final answer:
To find the circumference of the car tire, the speed 72km/h is converted to meters per minute, and then divided by the rotation rate of 400 revolutions per minute. The calculation reveals that the circumference of the tire is 3 meters.
Step-by-step explanation:
To calculate the circumference of the tire, we need to use the information given that the tire rotates 400 revolutions per minute and the car travels 72km/h. First, we convert 72km/h into meters per minute, since there are 1000 meters in a kilometer and 60 minutes in an hour.
72 km/h = 72 * 1000 meters/km / 60 min/h = 1200 meters/min
Now, we calculate the circumference by dividing the distance traveled in one minute by the number of revolutions per minute.
Circumference = Distance per minute / Revolutions per minute
Circumference = 1200 meters/min / 400 rev/min
Circumference = 3 meters/revolution
Therefore, the circumference of the tire is 3 meters.