change 40mph to inches/minute.
Then, revs= speed/(2PI*r)
A car is traveling at 40 mph. The radius of its wheels are 14 inches. How many revolutions per minute?
Please show work. I don't understand this.
3 answers
What is the Pl?
so 42,240/(2 x Pl*14)
so 42,240/(2 x Pl*14)
PI (π) is the ratio of the circumference to the diameter of a circle. So, there are 2π*14 = 28π inches in the circumference of the tire -- that's how far the car goes in one revolution of the tires.
Now it's just a matter of converting mi/hr to rev/min
40mi/hr * 1hr/60min * (5280*12)in/mi * 1rev/28πin = 480 rev/min
Now it's just a matter of converting mi/hr to rev/min
40mi/hr * 1hr/60min * (5280*12)in/mi * 1rev/28πin = 480 rev/min
1 answer