Math question

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So, I can't remember how to solve this. It's been years since I was in a math class or advanced physics where I did algebra all the time. Been exactly 18 years to be precise.

If I move at 1,500 miles per hour, I want to know how long it will take to reach 120 miles.

I think I figured it out, but I'm not quite sure. I took 1,500 divided by 120 and that gets me 12.5. I take 12.5 and divide it by 60 and that gets me 4.8. Thus 4.8 minutes to reach 120 miles. That seems like it's correct, but I'm not entirely sure. And if this is correct, I'm wondering what the 12.5 represents? What unit of measurement? Time or miles?

I'm asking because I fly the Raptor F-22 in FSX at mach 2.35 at 50,000 feet which is around 1,500 miles per hour ground speed. I want to know how long it will take before I reach my TOD (Top Of Descent). Granted this is only a Sim and I highly doubt the real life F-22 moves that fast for long durations. The heat build up on the wings would be catastrophic. I fly this fast when I travel around the world and to long distances.

Thanks.

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OK here's the maths if you are up for it!

Speed = distance/time

Rearranging this gives time=distance/speed

As a simple example time to travel 60 miles at 30 miles per hour is

60/30 = 2 hours

With your figures, t = 120/1500 = 0.08 hours (as your speed is in mph)

Multiplying this by 60 0.08x60 = 4.8 minutes

Not long, but then you are going pretty fast!

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Alan's got it, but o use a slightly different approach to memory: the ""per" in "miles per hour" means divide, so miles divided by hours.

Larry N.

As Skylab would say:

Remember: Aviation is NOT an exact Science!

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I'm asking because I fly the Raptor F-22 in FSX at mach 2.35 at 50,000 feet which is around 1,500 miles per hour ground speed. I want to know how long it will take before I reach my TOD (Top Of Descent). Granted this is only a Sim and I highly doubt the real life F-22 moves that fast for long durations. The heat build up on the wings would be catastrophic. I fly this fast when I travel around the world and to long distances.

Thanks.

True, as far as I know the F-22's use supercruise @mach 1.82.

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OK here's the maths if you are up for it!

Speed = distance/time

Rearranging this gives time=distance/speed

As a simple example time to travel 60 miles at 30 miles per hour is

60/30 = 2 hours

With your figures, t = 120/1500 = 0.08 hours (as your speed is in mph)

Multiplying this by 60 0.08x60 = 4.8 minutes

Not long, but then you are going pretty fast!

Thanks. Looks like my method was in reverse in reference to time. I took 1500/120 instead of 120/1500.

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True, as far as I know the F-22's use supercruise @mach 1.82.

It's amazing at what the Raptor can do. It's so maneuverable that the computer has to limit what the pilot can do otherwise he's kill himself. My guess is that perhaps one day they make the F-22 pilotless and then the full capabilities of the beast can be unleashed. Wouldn't that be something.

Both the B-2 and the F-22 are my all time favorite military aircraft in the U.S. inventory. Outstanding technology.