Calculus Hard Question
posted by Anonymous on .
A pendulum swings through an arc length of 1120 cm (Swing #1). With each further swing, the arc length is reduced by 15 %
State the growth factor.
Calculate the length of the arc in swing #5
I think im supposed to use this formula again, but I don't know how to use it. Tn = ar^n1

swing #1 : 1120
swing#2: 1120(.85) = 952
swing #3 : 952(.85) or 1120(.85)^2 = 809.2
..
swing#5 = 1120(.85)^4 = 584.647 cm 
Where did you get 0.85 from?

100%  15% = 85% = .85

Ok wait, sorry sorry. I actually messed writing the question. Its supposed to be 120 cm, not 1120 cm. But you're still right, the growth factor is 0.85m but I don't know how you got that:\

swing#5 = 120(.85)^4 = 63?

yes, to the nearest cm , I had 62.64

But I checked the answer, and it says its 73.695 :S

Ok, maybe I messed up writing the whole thing, I'll rewrite it again.
A pendulum swings through an arc of 120 cm (Swing #1)
With each further swing, the arc length is reduced by 15%
State the growth factor
Calculate the length of the arc in Swing #4 
Their answer is wrong.
According to your typing
swing#1 = 120
swing #2 = 120(.85) =
swing#3 = 120(.85)^2
swing #4 = 120(.85)^3 = 73.695
swing#5 = 120(.85)^4 = 62.64
Their answer would be for the 4th swing. 
Oh ok, thanks so much, it was all because of my typing mistake :S Sorry about that.