Asolid, homogeneous sphere with a mass of m0, a radius of r0 and a density of rho0 is placed in a container of water. initially the sphere floats and the water level is marked on the side of the container. what happens to the water level, when the original sphere is replaced with a new sphere which has different physical parameters? notation: r means the water level rises in the container, f means falls, s means stays the same.
the new sphere has a density of rho = rho0 and a mass of m < m0.the new sphere has a mass of m = m0 and a radius of r > r0.the new sphere has a density of rho = rho0 and a radius of r > r0.

b.a device that inputs heat into a cool object

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.