When two systems in contact are not at the same temperature, _____ occurs.expansionheat flowfrictionevaporation

Heat flow is the transfer of energy (heat) from the Earth's interior to its surface. The Earth's core cooling and radioactive heat creation in the upper 20 to 40 km of the crust are the main sources of heat on the planet.
Heat flow occurs when a hot item transfers its heat through a conductor to a cold object, similar to how high-energy objects impart their energy to low-energy objects.
How well a conductor transfers heat will impact how quickly and how much heat is transported.

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TorqueEffect TorqueEffect · Answer 2 · 2022-08-22T13:15:06+02:00

Answer:

Explanation:

When two systems in contact are not at the same temperature, Heat flow occurs.

more info:-

When two objects having different temperature are brought together, energy will always be transferred from the hotter (the object at higher temperature) to the cooler (the object at lower temperature).
The objects will exchange thermal energy, until thermal equilibrium is reached, i.e. until their temperatures are equal.
it can be explained by zeroth law of thermodynamics.