Which term describes the amount of heat needed to change 1 kg of a substance from solid to liquid at its melting point?

This is specific latent heat of fusion.

This is the heat needed to turn 1 kg of solid into a liquid at its melting point. When a substance changes its state from  solid to liquid form or from liquid to gas , heat energy is needed. This energy is used not to heat the substance but to separate the molecules from each other.

This energy is called latent heat energy. While a liquid is boiling and while a solid is melting, there is no temperature change. The temperature only changes when the change of state is complete.

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.

laticia draws the diagram below to show earth’s magnetic field.

answer

the arrows to the right of earth should point up.