Question

In water heat travels up much faster than it travels down explain

Answer 1

When there is heat at the bottom of water, the water molecules that are hot starts to move, thus the water molecules spread apart. The heated water becomes less dense. 

The less density water molecules rise to the top where it can find water with same density.

In this process, it pushes the other water molecules that were in its way. These molecules are pushed down.

At the same time, new water molecules fill the space left by the heated molecules that rose up. This brings a circular motion. Thus water heated at  the bottom travels up, cools down, gets denser, falls down. The cycle continues.

Answer 2

Heat moves through water by the process of convection - convection is when molecules of a fluid rise up when they get warmer accompanied by sinking of heavier cold molecules of the same fluid.

This movements of the fluid molecules is what is referred to as convection. Convection takes place due to the gain and loss of heat within a fluid. 

In fluids, warm molecules are lighter than cold molecules making the warm molecules rise above the cold ones, and the cold ones sink below the warm ones.  

The faster rise of water molecules, or any other fluid for that matter, is due to the fact that heated molecules gain higher levels of kinetic energy. When temperature rises within matter, the kinetic energy also rises. This makes the molecules to have more energy and move faster. 

As for the movement downwards, the cold water molecules that move down, have less kinetic energy and thus are slower. 

This explains the reason why water molecules move up faster than down during convection movements.