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as a person pushes a box across a floor, the energy from the person's moving arm is transferred to the box, and the box
and floor become warm during this process, energy is

As a person pushes a box across a floor, the energy from the person's moving arm is transferred to the box, and the box and floor become warm during this process, energy is conserved.

Explanation:

This process happens because of conservation of energy. According to the rule of the conservation of energy. Energy can’t be created not destroyed. It simply transformed or converted from one form to another. It simply means this system always need same amount of energy.

When a person moving arm is to transferred into box is form of kinetic energy and on the same way when then floor and box becomes warmer it converts into heat energy. Here the energy transformed into one to another form.  

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.