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Physics/Question on range to target


Honored friend, thank you for agreeing to answer questions, and I apologize for asking something that could be considered menial and annoying. But you see, I have a severe learning disability and this interferes with figuring out the answers to questions like the one below.

This is from a science fiction scenario, so I assume it makes a big difference that our friend the fictional character is firing an electromagnetic weapon that has an extremely high muzzle velocity, for which reason I think there will be almost no bullet drop. Now, our friend is shooting from 49.6 meters off the ground and he has the muzzle of his rifle depressed somewhat -- because he is firing from inside a clocktower. My angle measuring device says he is holding his rifle at a angle of -160 degrees, and it says that since he is standing upright, his feet are at -90 degrees.

This scope unfortunately has no mil dots, and its laser rangefinder is turned off. The target person is actually 1.86 meters tall, but when our friend the fictional character looks through the scope, then whatever the range may have been, objects looked 37.6% smaller. So then, can you estimate the range to the target? When I used an online calculator to solve for the hypotenuse, I felt I probably made some error, but I got 145 meters. Thank you very much.

Well, there's no exact answer here because I don't know the velocity.  Once you ignore that, and ignore the useless piece of information about the object appearing 37.6% smaller, then you just get a triangle.  You have a height difference, but I'm sure you're not trying to shoot an apple off of their head...even that isn't perfectly accurate information.  Basically you have a vertical distance of 47.7 meters and an angle that you gave of basically 70 degrees for the important distance.  That makes your hypotenuse 50.8m or 140m, depending on how you drew that angle (your directions are slightly ambivalent).  That gives you a range of 17m or 131m depending on the same question about your angle.  There's nothing else you can definitively say about this problem at all.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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