Communication disruptions caused by mobility in wireless sensor networks introduce undesired delays which affect the network performance in delay sensitive applications in MWSN. In order to study the negative effects caused by mobility, we propose a mathematical model to find the minimum cost path between a source node and a destination node considering the nodes position changes across time. Our mathematical model considers the usage of buffers in the nodes to represent the fact of storing a message if there is not an appropriate forwarding node for transmitting it. To contrast our mathematical model results we have designed two kinds of algorithms: the first one takes advantage of the closest neighbours to the destination node in order to reach it as fast as possible from the source node. The second one simply reaches the destination node if a neighbour node is precisely the destination node. Finally, we compare the delay performance of these algorithms against the mathematical model to demonstrate how efficient they are for reaching a destination node.