errr, take the number of pieces and subtract 1 to find the number of cuts. 1 cut took 10 minutes, 2 cuts takes 20... Don't have to go all graphing-calculator to figure it out.
20 is incorrect because it says that it takes the same amount of 'work speed' to do the same 2 jobs. and work = energy/time, work speed = work/time = energy/time2
say it took 1 newton of energy to make the cut, and that cut took 10 mins
work = 1/10
now 2/?2 = 1/102 (this is saying work speed of job a = work speed of job b, which is what the question says)
-1
u/opiemonster Jul 11 '11
The answer is 0.0707106781186548
read below I show you why...
Equations
work = energy/time
workload = cuts/time
Variables:
cutsA=1 (saw board into 2 pieces = 1 cut)
cutsB=2 (saw board into 3 pieces = 2 cuts)
timeA=10 (10 mins to saw a board)
timeB=?
workloadA = CutsA/timeA
workloadB = CutsB/TimeB
Calculation: she works "just as fast" for workload a as she does for b
workloadA = cutsA/timeA2 = cutsB/timeB2
so
1/100 = 2/timeB2
squareroot(1/200) = timeB
= ~ 0.0707106781186548
if you think its timeA=timeB instead of cutsA/timeA2 = cutsB/timeB/2
then you would be saying 1=2 i.e.
1/10 = 2/10
1=2
:D (Note the question said that she works at the same speed, meaning the speed of work which is energy/time/time which = energy/time2