Jolie builds a model of a maglev train. she uses disc
magnets to levitate the train. a disc magnet has its north and
south poles on its faces, as shown.
what is the best way to arrange the magnets on the train
and on the track so that the model train levitates?
flat, so that the north pole of each magnet on the train
points up and the north pole of each magnet on the track
points up
flat, so that the north pole of the magnets on the train point
up and the north poles of the magnets on the track point
down
on edge, so that the north poles of the magnets on the
train point to the front and the north poles of the magnets
on the track point toward the rear
on edge, so that the north pole of each magnet on the
tra and on the track point toward the rear of the train

this could be newton#'s law of cooling. the cooling curve is exponential

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.