Inertia is the tendency of an object to resist a change in . Newton’s first law of states that an object at rest will stay at rest unless it is acted upon by an outside force.

Inertia is an object's tendency to resist changes in its motion, so the first blank is “motion.” Newton’s first law is also called the first law of motion, making the same word fit the second blank. Weight and gravity do not describe what inertia resists.

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