Why vanderwall forces are weak forces?

Answer 1

The question should be, why is there a force at all! In the case of van der Waals forces, a.k.a. "induced dipole - induced dipole", there is no charge separation, or charge, present to begin with; only temporary dipoles caused by random movement of particles.

Answer 2

Van der Waals forces are relatively weak because they arise from temporary fluctuations in electron distribution around molecules. These fluctuations lead to temporary dipoles, inducing forces of attraction between neighboring molecules. Compared to stronger forces like covalent or ionic bonds, van der Waals forces are weaker due to their temporary nature and dependence on electron movement.