Un bloque de 2.5kg de masa es empujado 2.2m a lo largo de una mesa horizontal sin fricción por una fuerza constante de 16.0 N dirigida a 25° debajo de la horizontal. Encuentre el trabajo efectuado por: (a) la fuerza aplicada, (b) la fuerza normal ejercida por la mesa, (c) la fuerza de la gravedad, y (d) la fuerza neta sobre el bloque

Explanation:

(a) The applied force has two components Fx and Fy. The Fx component is the only one that does work

(b) There in no net force in the vertical component

(c)

(d)

I attached an scheme of the force diagram

mass and volume are the answers you are looking for

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.