A scientist places a strip of hot metal on top of a block of another metal with a lower melting point. The second metal quickly melts. What is the main type of heat transfer responsible?

Select one:
a. Convection, because the metals touch and cold from the block moves to the warmer strip of metal, cooling it down
b. Conduction, because both metals are in the sun and melt as the sun's rays heat them
c. Convection, because heat from the strip of metal heats the air around it, and then that warm air heats the metal block
d. Conduction, because the heat energy is absorbed by the metal atoms in the block. Once they have absorbed enough energy, they become liquid

D:

Explanation:

Conduction because the heat energy is transferring directly from the separate metals convection involves "currents" like in a liquid or a gas. When you turn on the stove with a pot of water on the burner the water at the bottom of the pot gets heated first almost immediately this water rises and cooler water falls. Basically the water is "stirring" or shifting, exchanging the heat energy this is why water heats so evenly.

D

Explanation:

The heat transfer that we'll have will be:

- At first, the metal bar will emanate heat through radiation, to the atmosphere, and to the second metal, through conduction.

- Because of this, the second bar will start to increase it's temperature, up to the fusion point, spending the energy received on the fusion, and also radiating heat to the atmosphere. It won't emit heat in any other form, since heat transmission can happen only from a hot body to a cooler one, and the only things in contact are the two bars.

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.