A physics class has been challenged with the task to design a device that allows the students to stand twenty feet apart and still catch water balloons without them breaking. In order to minimize the force at which the balloons collide with the catching partner, the students must test and evaluate many different designs. What best describes the independent and dependent variables in this experimental design? A) The balloon type of the independent variable and the collision impact is the dependent variable.
B) The collision impact is the independent variable while the device design is the dependent variable.
C) The engineering design of the catching device is the independent variable and the timing of the balloon catch is the dependent variable.
D) The engineering design of the catching device is the independent variable and the success rate of catching without popping is the dependent variable.

good looking response

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.