Question

which sentence describes newtons first law?
a. it takes a larger net force to accelerate an object at a greater rate.

b. the action force applied by one object to another is opposite in
direction to the reaction force.

c. forces always come in pairs that have the same magnitude.

d. unbalanced forces cause an object to move.

Explanation:

• Option A: Describes Newton's second law ($F = ma$), relating force, mass, and acceleration.
• Option B: Part of Newton's third law (action - reaction), but the full third law states action and reaction forces are equal in magnitude and opposite in direction, and this option is an incomplete description of the third law.
• Option C: Describes Newton's third law (action - reaction pairs have equal magnitude).
• Option D: Newton's first law (law of inertia) states that an object at rest stays at rest and an object in motion stays in motion with the same velocity unless acted upon by an unbalanced force. Unbalanced forces cause a change in motion (which can include starting to move from rest), so this describes Newton's first law.

Answer:

D. Unbalanced forces cause an object to move.