Two airplanes start at the same time and fly toward each other from points 1000km apart at rates of 420 km/h and 330 km/h. When will they meet?
2006-09-26 16:17:01 · 7 answers · asked by Solari 1 in Science & Mathematics ➔ Mathematics
d1=r1*t
d2=r2*t
d1+d2 = 1000 = 420t+330t
t(420+330) = 1000
t = 1000/(120+330)
2006-09-26 16:45:32 · answer #1 · answered by Helmut 7 · 0⤊ 0⤋
well i could do all the work for you .... or help you "think" about it and solve it yourself
as you know distance = rate * time
how quickly are they closing on each other? or in other words what is the rate of change of the distance between them?
or maybe being "concrete" helps ... ponder after 1 hour what has happened - plane A has gone 420 km towards plane B,
plane B has gone 330 km towards plane A .... so .... 750 km ....
[so hint hint hint u know this is going to take under 90 mins .... figure it out now]
oh and colliding airplanes typically isnt a good thing ...
2006-09-26 23:28:14 · answer #2 · answered by xkey 3 · 0⤊ 0⤋
This is two equations in which time is the variable you have to solve for. One of the distances will be set as negative, because they're moving in opposite directions. So one equation is:
1000km/h=420 km/h x T
the other is -1000km/h=330km/h x T
the time is set to a single equal time, because we want to know when they'll meet, so the 2 equations can be set as equal
solve each for T, then set them as equal and solve for h
as you asked, the answer will appear x hours after they leave.
2006-09-26 23:31:04 · answer #3 · answered by water boy 3 · 0⤊ 0⤋
they fly towards each other... thus
1000km/(420+330) kmperhour
= 1.33333... hours
= 80 minutes
2006-09-26 23:26:31 · answer #4 · answered by kb27787 2 · 0⤊ 0⤋
420x + 330x = 1000
750x = 1000
x = 1 hour and 20 minutes later
2006-09-26 23:25:28 · answer #5 · answered by Sherman81 6 · 2⤊ 0⤋
80 minutes.
2006-09-27 00:44:58 · answer #6 · answered by crazy8tiger 4 · 0⤊ 0⤋
approximately 1hr35mins
2006-09-26 23:31:22 · answer #7 · answered by cgf2us 2 · 0⤊ 0⤋