Answer
There is a large difference in pressure between the higher pressure on the outside and the lower pressure on the inside of a tornado. Objects in the path of a tornado can be ripped apart by the strong forces resulting from this large pressure difference.
Work Step by Step
The wind speed in the center of a tornado is greater than the wind speed at the outside. When air moves faster, then the pressure is lower, so there is a large difference in pressure between the higher pressure on the outside and the lower pressure on the inside of a tornado. Objects in the path of a tornado can be ripped apart by the strong forces resulting from this large pressure difference.
Note that $F = (P_2-P_1)~A$, where $F$ is the force, $P_2-P_1$ is the pressure difference, and $A$ is the area of the object.
