What will happen when two neutral objects are rubbed together?

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Explanation:

When two neutral objects come into contact--especially in a dry environment--electrons can be knocked loose from one object and picked up by the other. The object that gains electrons becomes negatively charged, while the object that loses electrons becomes positively charged. Objects with like charges repel each other, while those with opposite charges attract each other. This phenomenon--in which objects acquire an electric charge and exert a force on one another--is what we call static electricity.

d. air pressure decreases as altitude increases.

conduction, convection, radiation