After 2.5 hours, how fast is the distance between them increasing (in km/hr)
2007-12-17 12:18:07 · 4 answers · asked by Brian P 2 in Cars & Transportation ➔ Boats & Boating
i got 54.08 also but the answer is 21.63 km and i dont know how to get it
2007-12-17 12:28:38 · update #1
54.08 Kilometers
2007-12-17 12:25:31 · answer #1 · answered by Anonymous · 0⤊ 1⤋
You have the answer at the distance between them after 2.5 hours of travel, but your question is how fast the distance is increasing.
Divide your answer by 2.5, or time traveled to get the correct answer.
2007-12-19 21:49:43 · answer #2 · answered by Frank N 5 · 0⤊ 0⤋
Hi
Just divide the 54.o83269 by 2.5 (hrs travelled)
= 21.633
2007-12-18 11:15:52 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Let's see ...
Let dA/dt = 12, dB/dt = 18.
After 2.5 hours, A has traveled 30 km, and B has traveled 45 km. By the Pythagorean Theorem, the distance between them is sqrt(2925).
A^2 + B^2 = D^2, where d is the distance between them.
2A*dA/dt + 2B*dB/dt = 2D*dD/dt
2(30)*12 + 2*45*18 = 2*sqrt(2925)*dD/dt
2340 = 2sqrt(2925)*dD/dt
1170 = sqrt(2925) * dD/dt
1170 = 15sqrt13* dD/dt
1170/(15sqrt13) = dD/dt
78(sqrt 13)/13 = dD/dt
The distance between them is increasing
78(sqrt13)/13 = 21.633 km/hr
2007-12-17 20:27:03 · answer #4 · answered by jenh42002 7 · 0⤊ 0⤋