de Broglie wavelength is λ==

where λ is wavelength, h is Planck's constant, m is the mass of a particle, moving at a velocity v and k is the momentum.

∴ According to above relation, If particle velocity, mass, momentum or its kinetic energy increases, de Broglie wavelength decreases.

Same momentum particles have same de Broglie wavelength.

If velocity is constant heavier mass particle will have smaller de Broglie wavelength. Similarly it applies for kinetic energy.

If particle falls from same height, velocity will be same irrespective of its mass.