Why dose the weight of an object change with increasing elevation on earth

Because the strength of the gravitational forces between two objects
depends on the distance between the objects' centers, and when your
elevation changes, so does the distance between your center and the
center of the Earth.

How is it possible that phylogenies based on sequences from nuclear genomes and organellar genomes (i.e., chloroplasts and mitochondria) from the same group of species yield phylogenetic trees with different branching orders?   answer :   the genome of the endosymbiont is more closely related to members of the group in which it originally evolved, while the nuclear genome of the engulfing organism has its own evolutionary trajectory.