1. There are stars whose brightness varies periodically. These stars are called pulsating stars. An astronomer hypothesizes that the time taken t for the star to undergo one oscillation depends on the star’s density ρ, the star’s radius r and Newton’s Gravitational constant G. Newton’s Gravitational constant G has dimensions M-1L3T-2. A. i. State the dimension of t.
ii. Determine the dimension of ρ.
iii. State the dimension of r.
B. Use dimensional analysis to predict the form of the equation for the time taken t for the star to undergo one oscillation. Include all steps and assumptions made.

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.

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.

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.