Plane Flying with a TailwindDate: 9/8/96 at 20:48:56 From: Anonymous Subject: Plane Flying with a Tailwind A jet is flying 2400 miles from Hawaii to San Francisco. In still air, it flies at 600 mph. There is a 40 mph tailwind. How many hours after takeoff would it be faster to just go to San Francisco than to return to Hawaii in the case of an emergency? I need the formula to solve this problem. My teacher told us the answer is 1.75 hours. I tried dividing 640mph into 1200 (midpoint of travel) and got 1.875 hours. Then I thought that if one was to turn around after flying 1.75 hours, that it would take longer to get back to Hawaii because the speed would be 560 mph. I can't visualize this - can you help me? Thanks! Date: 9/9/96 at 11:49:23 From: Doctor Robert Subject: Re: Plane Flying with a Tailwind Flying TO San Francisco, the plane's speed is 640 mph. If it were flying back to Hawaii, its speed would be 560 mph. Let t be the number of hours of flight. Then it has flown a distance of 640t miles and the distance yet to go is 2400 - 640t. The time left to fly is then (2400-640t)/640. However, if it were to return to Hawaii, it would have to fly 640t miles at 560 mph which would then take 640t/560 hrs. If we equate these times we have (2400-640t)/640 = 640t/560 If you solve this equation for t you get t = 1.75 hr. -Doctor Robert, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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