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Brainiac71 · Jul 30, 2013, 08:42 PM

Two planes are flying around. 1st Plane is flying at 300 miles per hour and is 350 miles ahead of the 2nd plane. 2nd plane is flying at 400 miles per hour. How long will it take for the 2nd plane to catch up to the 1st plane?

teacherjenn4 · Jul 30, 2013, 08:44 PM

We'll help, but we won't do your work for you. Post your attempt and we'll help you from there.

Brainiac71 · Jul 30, 2013, 08:49 PM

Originally Posted by teacherjenn4

We'll help, but we won't do your work for you. Post your attempt and we'll help you from there.

I tried 300 over 250 equaling 450 over x.
I multiplied 250 and 450. My answer was a huge number.
I got 112,500. THen, I divided it by 300. Final answer was 375. This
does not look right. I need to convert it into hours and minutes. Am I doing this correctly?

Help!

ebaines · Jul 31, 2013, 05:43 AM

Originally Posted by Brainiac71

I tried 300 over 250 equaling 450 over x.
I multiplied 250 and 450. My answer was a huge number.
I got 112,500. THen, I divided it by 300. Final answer was 375. This
does not look right. I need to convert it into hours and minutes. Am I doing this correctly?

Help!

Try this instead: imagine you are sitting in plane 1 cruising at a steady speed. What is the relative speed of plane 2 compared to you? How long would it take plane 2 to cover the 350 mile gap at that relative speed?

Alternatively you can try this: use the equation $x= x_0 + v_0t + \frac 1 2 a t^2$ . For both planes acceleration is 0. The position of the first plane as a function of time, given that it has a 350 mile head start, is therefore:

$x_1 = 350 miles + (300 \frac {miles}{Hr} \times t)$

The position of plane 2 is:

$x_2 = 0 + (400 \frac {miles}{Hr} \times t)$

When they meet up you have $x_1 = x_2$ . Solve for t.

I suggest you try solving the problem using both methods so that you get comfortable with these techniques.