Heat is a form of energy, and energy itself does not have weight. Weight is a measure of the force exerted on an object due to gravity, which depends on the mass of the object. Heat, on the other hand, is the transfer of thermal energy between objects or within an object. It is associated with the motion and vibration of molecules and atoms.
When heat is transferred from one object to another, it does not add any mass to the objects involved. Instead, it increases the internal energy of the objects, causing the particles within them to move faster. This increase in energy does not change the mass of the objects, and therefore heat itself does not possess weight.
It's important to note that while heat doesn't have weight, it can affect the weight of an object indirectly. When an object absorbs heat, its temperature may increase, causing its volume to expand due to thermal expansion. This expansion can result in a change in the object's weight when measured using certain weighing techniques, such as with sensitive balances. However, the weight change is not due to the heat itself but rather the physical expansion or contraction caused by the temperature change.