How do scientists describe the condition of an unbalanced force?

Any kind of pull or push is a force. In order to illustrate a force, one must be familiar with two things. One must be familiar with the direction of the force and the size of the force. The forces, which are equivalent in size but in opposite direction are known as the balanced forces.  

The balanced forces do not result in a change in motion. When the balanced forces function on an object at rest, the object will not move. The forces, which results in a change in the motion of an object are known as the unbalanced forces. The unbalanced forces are not opposite and equal.  

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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