About wind resistance...

[yarrr]

Originally Posted by sbergman27

the power required to overcome wind resistance increases as the *cube* of the speed.(!)

Total power to maintain a particular speed. (50 mph = '1'):

50 mph : 1.00
55 mph: 1.22
60 mph : 1.46
65 mph: 1.75
70 mph: 2.07
75 mph: 2.44

50^3/50^3 = 1
55^3/50^3 = 1.331
60^3/50^3 = 1.728
65^3/50^3 = 2.197
70^3/50^3 = 2.744
75^3/50^3 = 3.375

[sbergman27]

Originally Posted by yarrr

50^3/50^3 = 1
55^3/50^3 = 1.331
60^3/50^3 = 1.728
65^3/50^3 = 2.197
70^3/50^3 = 2.744
75^3/50^3 = 3.375

That's what the wind resistance looks like. But the total resistance is the wind resistance + the mechanical friction.

We're assuming, for the sake of this discussion, that at 50 mph they are equal. For simplicity, let's call each value "1".

So the total resistance at 50 mph is 1 + 1 = 2

Looking at it that way, at 75 mph, the power going to overcome wind resistance goes to 3.375, as you say. The power going to mechanical friction goes to 75/50 = 1.5

3.375 + 1.5 = 4.875 is then the total resistance. At 50 it is 2.

4.875 / 2 ~= 2.44

So the total resistance at 75 mph is 2.44 times the resistance at 50 mph.

Sorry I didn't go into more detail in the original post. I got lazy. ;-)

-Steve