Yes, you can , but you need a handle of some kind to hold the can.
Convection currents. This means that the soup that is heated moves away from the heat, and the cool soup flows over heat so that warms up
the aboriginal people used wood and rubbed stones to make the fire and put the food over it
Radiated
Transferring heat from the soup to your breath. If you have a pot of hot water and then moc it with cold water, the two will heat exchange until the temperature through out the water is the same. It's the same principle.
Yes, it should be safe to heat it over a fire in the opened can.
through radiation
you cook the tomato soup in a pan and slowly pour in the milk while stirring over medium heat
A cold spoon will extract heat from the soup, a spoon that is warmer than the soup will transfer heat to it.
Standing over a bonfire, you feel heat because heat is being transferred to your body by radiation. The fire emits infrared radiation that warms your skin and clothes, resulting in the sensation of heat. The closer you are to the fire, the more intense the heat will feel due to the increased radiation exposure.
Fire you idiot. They suspended the pots over a fire with a tripod like set of sticks with the pot attached to the sticks by a cord.
Heat, smoke, fire...
Endothermic, the soup is taking in heat to boil.