robphy's latest activity
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robphy replied to the thread Prove that the integral is equal to ##\pi^2/8##.Possibly helpful: $$\frac{\left(\left(\cos x\right)^{2}-\left(\sin x\right)^{2}\sqrt{9-16\left(\sin x\right)^{2}}\right)}{1-\left(\tan... -
robphy replied to the thread I A "continous" gravitational field formula r=0 to infinity.As I suggested above, here is an implementation in Desmos: www.desmos.com/calculator/yvk5ej85vu
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robphy reacted to Owe Kristiansen's post in the thread I A "continous" gravitational field formula r=0 to infinity with
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This model describes the gravitational field of a non-rotating, spherically symmetric body—without spin effects such as centrifugal... -
robphy replied to the thread I A "continous" gravitational field formula r=0 to infinity.These “logical expressions” comprise a sometimes useful computational trick to avoid case-statements, as you say. This can be...
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robphy replied to the thread Prove that the integral is equal to ##\pi^2/8##.With some context (e.g, a plot or some geometric figure), there may be symmetries that could be exploited to simplify the calculation...
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robphy reacted to pines-demon's post in the thread Prove that the integral is equal to ##\pi^2/8## with Like.
What is the actual statement or context of this integral? Does it explictly say that it can be calculated using Fubini's theorem? Or is...
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robphy replied to the thread Writing a vector parallel and normal to a unit vector ##\hat n##.When learning relativity, this decomposition was one of my "a-ha" moments because I could see the use of the vectors ##\vec A## and (not...
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robphy reacted to Orodruin's post in the thread Writing a vector parallel and normal to a unit vector ##\hat n## with Like.
I actually think ##\vec A - (\vec A \cdot \hat n)\hat n## is nicer than the double cross product. It also generalises to any dimension.
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robphy replied to the thread I Visualising rotation in 3-D space.If your axis of rotation is along the z-axis, the disk represents the unit-disk on the xy-plane. Vectors parallel to the axis of...
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robphy replied to the thread I Visualising rotation in 3-D space.It might help to draw a disk centered at the origin whose normal is along the axis of rotation. www.desmos.com/3d/gflyvyyuoh
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robphy replied to the thread Desmos Auto Embeds.Thanks!! Can this be done for Desmos' "geometry" as well? www.desmos.com/geometry/fui45vl7ct https://www.desmos.com/geometry/fui45vl7ct
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robphy replied to the thread [ASK] Trigonometric Inequality.Possibly useful visualization: www.desmos.com/calculator/omyivs9dzs
