# Homework Help: Motion in 1D direction, kinematics

1. Sep 18, 2009

### darklich21

1. The problem statement, all variables and given/known data

A jetliner leaves San Franciso for New york, 4600 km away. With a strong tailwind, its speed is 1100 km/hr. At the same time, a s2nd jet leaves New York for San Francisco. Flying into the wind, it makes only 700 km/hr. When and where do the two planes pass each other?

2. Relevant equations
x=x0 + v0T + 0.5at^2
Vf^2=Vi^2 + 2ad
Vf= Vi + at

3. The attempt at a solution

Basically, from what I know I'm going to make 2 separate sets of equations and somehow equate them, 1 of them in terms of distance, and another one in terms of time. But I don't really know where to start.

the answer was given to me, they'll be at the same point 2.5 hours later @ 2000km. I dont know how to get this. Please help.

2. Sep 18, 2009

### Anden

A hint: How long distance has the planes travelled together when they meet?

3. Sep 18, 2009

### rl.bhat

When the planes meet, duration of flight time must be the same.
In that time interval, one plane has traveled x km and the other (4500 - x ) km.

4. Sep 18, 2009

### darklich21

Well I need to find both the time they meet, and the distance where they meet. But how would I set this up in terms of an equation?

5. Sep 18, 2009

### rl.bhat

Both the planes are moving with uniform velocity. What is the relation between the velocity, time and distance?

6. Sep 18, 2009

### darklich21

D=vt

7. Sep 18, 2009

### darklich21

Im not seeing how that helps me at this point. Doesn't this problem have something to do with equating equations or something of the sort?

8. Sep 18, 2009

### darklich21

I had a bit of a break through, Ok so I found the time at which they will be at the same distance, which was 2.4 hours. I did 4600km/700km/hr= 6.57hr, which is how long the 2nd plane would take to reach the other side, and I also did 4600 km/1100km.hr which is 4.18 hours, which is how long it would take the first plane to reach the other side from where the 2nd plane started.

But how would I find the distance

9. Sep 18, 2009

### rl.bhat

t = x km / (1100 km/h) = (4500 - x) km/( 700 km/h)

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