Dawood ibn Kareem
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If randomness doesn't exist, how come the universe isn't a perfect sphere with predictable distribution of matter?
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14 votes

This is a superb question, because it gets to the core of one of the great debates of 20th century physics - the nondeterministic interpretation of the laws of quantum mechanics (that is, the universe ...

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Why does adding red light with blue light give purple light?
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10 votes

The answer to this is to do with how the brain responds to the stimulation of the S, M and L cones in different ratios. This is best seen in the standard CIE XY chromaticity chart. The points on ...

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Why is velocity of the mass $v/ \cos θ $? Why not $2v \cos θ$?
6 votes

Imagine what would happen if the two pulleys were very close together, so that $\theta$ is very close to zero, and $\cos\theta$ is very close to one. In that case, the mass in the middle will rise ...

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Why is it easier to carry a person while spinning than not spinning?
5 votes

Your friend is not actually lighter when you're spinning, obviously. But she seems lighter, because she is easier to balance than when you're not spinning. This is a gyroscopic effect - it's the same ...

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Why does induced current depend on the area of a loop of wire?
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4 votes

Imagine a wire shaped like a long thin rectangle, with an ammeter at one end. It's in a constant magnetic field that's perpendicular to the plane of the rectangle. Now move the rectangle in a ...

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Winter solstice, sunrise and sunset time
3 votes

Solar days Solar noon is the time of day when the sun reaches its highest point in the sky, as seen from any particular place on the earth's surface. A solar day is the length of time that passes ...

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Elliptical orbit of revolution of earth
2 votes

There are essentially five solutions to the two body problem, where the bodies are attracted to each other by gravity. A hyperbolic path - the two bodies are moving away from each other too quickly ...

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Energy efficiency: better to heat hot tub constantly or twice a day for a longer period?
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2 votes

From your description, it sounds like "standard mode" keeps the water always at approximately 38 degrees, whereas "economy mode" lets the water get cooler than this often. When the water is cooler ...

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How many minutes in a year?
2 votes

The geocentric illusion One astronomical year is the amount of time it takes the earth to complete an entire revolution around the sun. During that time, the earth spins on its axis (approximately) ...

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Potential of cells in series
2 votes

Imagine connecting these two cells into a circuit, with some other components. Electrons will move through the wires of the circuit. When the electrons reach the positive terminal of a cell, new ...

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Zero energy universe does not make sense
2 votes

Every particle in the universe attracts every other particle, by gravity. There are other forces between them too, but over all, there's lots of mutual attraction going on. Now, suppose you wanted ...

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Why the Earth does no work on the satellites that revolve around it?
1 votes

If there were no gravity, each satellite would carry on in a straight line, and eventually get further and further from the earth. But the earth's gravity pulls them in. However, if the satellite ...

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Why is current the same in a series circuit?
1 votes

Current is a measure of how many electrons go past a particular point in the circuit every second. So there are electrons rushing into one side of the light bulb, and rushing out of the other side. ...

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