Alai is comparing the physical property of two materials. he is hitting each with a hammer to observe what happens. what physical property of the materials is alai most likely observing? solubility conductivity hardness odor

Alai is most likely observing the hardness of the materials.

Explanation: Hardness is defined as the property of a material to resist a change in its structure when applied to a external force.

Hard materials will not change their shape when they are hit with a hammer whereas soft materials will  change their shape when they are hit with a hammer.

All the three statements are all true. Although, statement I is true for Netwon's first law of motion, but statement II supports the Newton's third law of motion and statement III supports Newton's second law of motion.

Explanation:

Examining the statements one at a time

I. A body can remain at rest when it is under the action of external forces.

This is obtained from the teachings of the Newton's first law of motion.

Every object continues in its state of rest, inertia or uniform motion unless acted upon by an external force. For a body at rest or in a state of uniform motion, the external forces acting on the body isn't necessarily strictly required to be zero. The most major point is that the resultant of all of the external forces has to be zero for the body to remain at rest or a state of uniform motion.

II. The forces of action and reaction have resulted in zero, always causing the balance of the body in which they act.

This is obtained from the Newton's third law of motion that action and reaction are equal and opposite. The reactive force is always due to the active force and it is always equal and opposite to this active force that together, they form a system of forces with resultant of zero and leading to the balance of the bodies on which they act.

III. The force applied to a body, by Newton's Second Law, is the product of its mass by the acceleration that the body has.

This is the most basic Interpretation of the Newton's second law, F = ma.

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