



 
Hi Christina. Every time the wheel turns once around, the car has moved ahead by the circumference of the tire. You know the diameter of the tire, so you can calculate the circumference from that. Let's say the circumference is C feet. The rest of the problem is really just unit conversion: 50 miles / hour = 50 5280 / 60 feet / minute = 4400 feet / minute If one revolution is C feet, then 4400 feet per minute is how many revolutions per minute? For part B, you just need to remember that each revolution is 2π radians and multiply this by the answer for part A. Hope this helps,  


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