The transfer of energy as heat caused by the collision of molecules is called

Explanation:

The transfer of energy as heat, i.e. heat transfer, is the transfer of kinetic energy due to difference in temperatures of the bodies: heat is transferred from warmer objects to cooler obects.

This heat transfer may occur by three different means:

Conduction is the transfer of heat between objects in direct contact and is due to the transfer of kinetic energy among neighbour particles (atoms or molecules) which are in constant vibration and colliding one to each other. The hotter particles are vibrating faster than the cooler ones, and, so, during the collisions the faster particles trasfer kinetic energy to the quiter particles.

For example, when you heat the tip of a needle the heat will be transfered from the tip to the rest of the needle by conduction.

Convection is the transfer of heat by the motion of fluids (gases or liquids), again the hotter particles, which have greater kinetic energy, transfer their energy to the cooler particles, but in this case the fluid moves.

Radiation is the heat transfer by electromagnetic waves; again from hotter objects to cooler ones. Since electromagnetic waves travel through vacumm, radiation does not need a physical medium.