Each second after shut-off, the speed of the blade is 2/3 of the speed in the previous second. After the first 8 s, the saw has turned 258 times. What was the speed of the saw before the motor shut off, to the nearest tenth of a turn per second?
I get 805.4 but I don't think I'm right.
3 answers
i wanna answer this inequality of this graph f(x)= x -3 if x >= 3
You want the sum of the first 8 terms:
S8 = a(1-r^8)/(1-r) = a(1-(2/3)^8)/(1/3) = 2.883a
So, a = 258/2.883 = 89.49
Your answer is totally unreal. It would have turned 805.4 times in the 1st second, which is way more than the total turns after 8 seconds. I hope that is why you doubted it, and not just a vague uneasiness.
S8 = a(1-r^8)/(1-r) = a(1-(2/3)^8)/(1/3) = 2.883a
So, a = 258/2.883 = 89.49
Your answer is totally unreal. It would have turned 805.4 times in the 1st second, which is way more than the total turns after 8 seconds. I hope that is why you doubted it, and not just a vague uneasiness.
Thanks Steve, turns out my calculator is a bit sensitive..
1 answer