Question

1. what is an isolated system?

a. a system in which the net internal force is zero
b. a system in which the net external force is zero
c. a system in which the net internal force is a nonzero constant
d. a system in which the net external force is a nonzero constant

Explanation:

To determine the correct answer, we recall the definition of an isolated system in physics (a subfield of Natural Science). An isolated system is one where the net external force acting on it is zero. Let's analyze each option:

• Option a: Internal forces within a system (like forces between parts of the system) don't define an isolated system. The net internal force is always zero due to Newton's third law (action - reaction pairs), so this is incorrect.
• Option b: This matches the definition of an isolated system. When the net external force is zero, the system is isolated (for example, in the context of conservation laws like conservation of momentum).
• Option c: As mentioned, net internal force is zero, not a non - zero constant, so this is incorrect.
• Option d: If net external force is non - zero, the system is not isolated (external forces are acting on it), so this is incorrect.

Answer:

b. A system in which the net external force is zero