A carpenter glues a pair of cylindrical wooden logs by bonding their end faces at an angle of $\theta = 30^{\circ}$ as shown in the figure.

The glue used at the interface fails is

Criterion 1: the maximum normal stress exceeds $2.5$ MPa

Criterion 2: the maximum shear stress exceeds $1.5$ MPa

Assume that the interface fails before the logs fail. When a uniform tensile stress of $4$ MPa is applied, the interface

1. fails only because of criterion $1$
2. fails only because of criterion $2$
3. fails because of both criterion $1$ and $2$
4. does not fail