Each tire on a truck has a radius of tires 18 inches. the tires are rotating at 50 revolutions per minute. find the linear speed of the truck

Each rotation of the tires will cause the truck to move forward by the circumference of the tires. So C = 2*pi*r C = 2*pi*18 C = 113.0973355 inches Now the tires is rotating 50 times per minute, so let's multiply the circumference by 50 to get the number of inches per minute. D = 113.0973355 * 50 D = 5654.866776 in/min So the linear speed of the truck is 5654.866776 inches per minute. But that unit of measure is rather inconvenient. Let's convert to ft/second. 5654.866776 in/min / 60 sec/min / 12 in/ft = 7.853981634 ft/sec. So we can also express the linear velocity as 7.853981634 ft/sec. Since we have a truck, perhaps miles per hour would be a more reasonable unit. So 7.853981634 ft/sec / 5280 ft/mile * 3600 sec/hr = 5.354987478 mph. And if you desire, you can convert to many other units of measure, such as meters/second, kilometers/hour, furlongs per fortnight, etc. So in conclusion, the linear velocity can be expressed (to 2 significant figures) as any of: 5600 in/min 7.9 ft/sec 5.4 mph