Question

Two objects, A and B, are rubbed together. As a result, object A acquires an excess negative charge while object B becomes positively charged. In comparison to their masses before the charging process, you can say that

A. the mass of both objects decreased.
B. the mass of A increased and that of B decreased.
C. the mass of both objects increased.
D. the mass of A decreased and that of B increased.

Answer 1

During the process of charging by friction, object A gains electrons and mass, while object B loses electrons and mass. Hence, the mass of object A increases and the mass of object B decreases.

Step-by-step explanation:

When objects are rubbed together, such as amber and cloth, charge is transferred from one object to another. In this process, object A (amber) becomes negatively charged as it gains electrons, and object B (cloth) becomes positively charged as it loses electrons. The key point to remember is that electrons have mass, although very small (approximately 9.109 x 10-31 kg). When object A gains electrons, it gains this small amount of mass. Conversely, when object B loses electrons, it loses a small amount of mass.

Therefore, the mass of object A (amber) has increased slightly, and the mass of object B (cloth) has decreased slightly. However, the change in mass is generally too minuscule to measure with ordinary equipment.

The answer to the student's question is B. the mass of object A increased and the mass of object B decreased.