Two jets leave St. Louis at 2 P.M., one traveling north at 850 km/h and the other south at 750/km/h. At what time will they be 4000 km apart?
Answer is 4:30PM.
How can I solve this?
I've written this chart, but I think I did it completely wrong.
--------Rate x Time = Distance
Jet1 = 850 ||| 1 |||||||||||||||| 850
Jet2 = 750 ||| 1 |||||||||||||||| 750
2007-11-21 04:06:11 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
RELATIVE speed is 850 - (- 750) km/h = 1600 km/h
t = 4000 / 1600 h
t = 40 / 16 h
t = 2 ½ h
Answer is 4:30 pm
2007-11-25 04:08:52 · answer #1 · answered by Como 7 · 0⤊ 0⤋
Jet₁ and Jet₂ traveling in opposite directions is the same as Jet₁ staying still while Jet₂ speeds up to (850+750) = 1600 km/h.
4000km * (1h/1600km) = 2.5h after starting time (2pm)
The jets are 4000km apart at 4:30pm
2007-11-21 12:14:15 · answer #2 · answered by DWRead 7 · 1⤊ 0⤋
their total speed is 850+750=1600km/h(since they are flying in opposite direction)
in order to be 4000km apart, it takes 4000/1600=2.5hr=2hr30min
add 2.5 hr to 2pm is 4:30pm
2007-11-21 12:13:14 · answer #3 · answered by someone else 7 · 1⤊ 0⤋