The following question is lowing question, include units. optional! to receive full credit for the fol you muust show your work and your final answer must 5. (10 points (bonus)) the source of the sun's energy is a sequence of nuclear re- occur in its core. the first of these reactions involves the collision actions that or to protons, which fase together to form a single mucles that weighs les than the e two separate protons thus releasing energy. for this "nuclear fusion" process to occur, the two protons must first approach until their surfaces are essentially touching. (a) (6 points) assume both protons are moving with the same speod and they collide head-on. the radius of a proton is approximately 1.2 x io-s m, use thi is to estimate the minimum speed that will allow fusion to occur. (b) (4 points) you may recall from thermodynamics that the average trans- energy of a particle in a gas at temperature t is jkbt lational kinetic where kp is the boltzmann constant 1.4 x 10-23 j/k. what is the mini- mum temperature of a star where the proton-proton nuclear fusion above is occurring?

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible

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.