Jawabanmu

2014-09-07T18:09:08+07:00
Diketahui :
 l_{1} = 1 m \\  l_{2} = 1,2 m \\  f_{L} = 3,3
ditanya : v = ..?
jwb :
f_{L}  = f_{1} -  f_{2} \\ f_{L}  =  \frac{v}{2.l_{1}} -   \frac{v}{2.l_{2}}  \\ 3,3 =  \frac{v}{2.1} -  \frac{v}{2.1,2} \\ 3,3 =  \frac{v}{2} -  \frac{v}{2,4}  \\ 3,3 =  \frac{1,2v - v}{2,4}  \\ 7,92 = 0,2 v  \\ v =  \frac{7,92}{0,2} \\ v = 3,96

check ulang hitungannya ya semoga membantu:)
4 3 4