Opening up a Laptop

One equation in physics is torque, which is the Force applied to object to rotate it about an axis times the radius the force is applied at. Torque only takes into account the force perpendicular to a surface, because any other direction will not cause it to spin.

When you open up a laptop, either with a force at some angle or directly perpendicular, the force acting perpendicular causes a net torque and spins it about the axis.

The same can be seen on doors, and even books. Also, some caps that come on hinges, like a lotion bottle, can be described in this way. As long as some of the force is directly perpendicular, the surface will move in the way it is being pushed or pulled.