The motion of the sheet of paper which falls down freely, is analyzed by the method of dynamics. In the previous work, we discussed the motion of the sheet of paper which goes inside the delivery unit of printing machine and rotates around a cylinder. In those cases, no outer force was considered except the force pulling the edge of a sheet of paper. In this work, we considered the outer forces, gravity force and fluid force. Generally, the analysis of the flow around the object is very complicated, and the fluid force affecting the object is difficult to solve. So, we analyzed the fluid force by considering the flow momentum. In this work, we analyzed the case of a sheet of free falling paper. In the future work, we are going to adopt the method discussed in this work to the sheet of paper which goes inside the printing machine.
