Recent content by grouper

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    Calculating Time Dilation for a Spacecraft Traveling to Proxima Centauri

    Ok, working that out I got v=0.759c and Δt according to the Earth observers is 5.68 years, both of which are correct. Thanks for the help.
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    Calculating Time Dilation for a Spacecraft Traveling to Proxima Centauri

    Thanks for the equation corrections! How do I figure out v without knowing Δt though? (or vice versa?)
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    Calculating Time Dilation for a Spacecraft Traveling to Proxima Centauri

    Homework Statement The nearest star to Earth is Proxima Centauri, 4.3 light-years away. At what constant velocity must a spacecraft travel from Earth if it is to reach the star in 3.7 years, as measured by travelers on the spacecraft ? How long does the trip take according to Earth...
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    Focal length eyepiece for telescope

    Yeah, I don't know either. I mean, that explanation makes sense in the context of defining everything that way but it goes against what we learned in class about telescope design and use. Oh well. At least I got the point for that problem.
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    Angular Separation of Stars: Min Resolved w/ Diffraction Effects

    I figured out the problem; they were asking for arcs. Wasn't indicated anywhere but I eventually gave up on this problem since it's due tonight and when it showed the correct answer it read "0.46' of arc". Would've been nice if they said that in the problem, especially considering all the...
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    Focal length eyepiece for telescope

    Luckily we're allowed to guess as many times as we want so I just started plugging in numbers because I figured it had to be around 17 cm. I eventually got the right answer with 10 cm. Not sure how they got that though, I'll have to bring it up with my professor. This online thing we use...
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    Focal length eyepiece for telescope

    No, it's in meters and automatically only grades the first two significant figures. I'm not sure what's wrong. We both must be making an assumption that isn't correct since we both got the same answer. I have until tonight, I'll look around elsewhere on the web for some hints, but if you...
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    Focal length eyepiece for telescope

    Ok, I understand how you did that and I agree the answer should be f=0.167 m either way. It's an online program though and it keeps telling me that that answer is incorrect. It's due tonight and I'm not sure what else to do with this problem.
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    Focal length eyepiece for telescope

    Using do=0.10026 m and di=-0.25 m yields f=0.167m, which is also incorrect. Our AI hinted that all of homework problems in this assignment use Rayleigh's criterion though, so I think this is the wrong way to go about it. I'm not sure how to apply Rayleigh to this situation though.
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    Angular Separation of Stars: Min Resolved w/ Diffraction Effects

    I suppose either a smaller wavelength or a larger diameter; do you think I should be using a different λ for my estimation? If I use λ=400 nm (keeping D=5.0 mm), that yields θ=9.76e-5 rad, but that's not correct either. I got the 5.0 mm diameter from another problem, so I'm not sure adjusting...
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    Angular Separation of Stars: Min Resolved w/ Diffraction Effects

    Homework Statement What is the minimum angular separation an eye could resolve when viewing two stars, considering only diffraction effects? Homework Equations θ=(1.22*λ)/D The Attempt at a Solution I tried estimating with λ=550 nm and D=5.0 mm (pupil diameter) which appeared in...
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    Focal length eyepiece for telescope

    Homework Statement Suppose that you wish to construct a telescope that can resolve features 7.0 km across on the Moon, 384,000 km away. You have a 2.2 m-focal-length objective lens whose diameter is 10.5 cm. What focal-length eyepiece is needed if your eye can resolve objects 0.10 mm apart...
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    Maximizing Telescope Resolution: Finding the Optimal Eyepiece Focal Length

    Still haven't figured this one out if anybody has any suggestions at all; it's due this weekend.
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    Minimum angular separation for viewing stars

    No, I tried that. I don't think estimation is what this problem is getting at. There's got to be some way to tease some of the variables out; perhaps by assuming the distance to be infinity, even though that's not correct. I'll keep playing around with it; it's due this weekend.
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    Minimum angular separation for viewing stars

    It's an online thing so it tells me when I get it wrong but I can't see the right answer unless I want to give up and lose that point. I'll think about it some more.
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