Let's go through each scenario and identify which of
Newton’s Laws of Motion it describes. Here are the three laws for reference:
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Newton’s First Law (Law of Inertia): An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an unbalanced force.
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Newton’s Second Law (F = ma): The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
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Newton’s Third Law (Action-Reaction): For every action, there is an equal and opposite reaction.
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1. The soccer ball is motionless on the ground. It remained motionless because no one kicked it.
✔ Newton’s First Law of Motion
Explanation:
The ball is at rest and remains at rest because there is no unbalanced force acting on it. This illustrates inertia — an object will stay at rest unless a force acts on it.
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2. The force of tennis racquet hitting the tennis ball is equal in magnitude and opposite in direction of the force of the tennis ball pushing back on the racquet at their point of contact.
✔ Newton’s Third Law of Motion
Explanation:
When the racquet hits the ball, the ball exerts an equal and opposite force on the racquet. This is a classic example of action-reaction pairs: for every action (racquet hitting ball), there is an equal and opposite reaction (ball pushing back on racquet).
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3. The force of the tennis racquet hitting the tennis ball caused the tennis ball to change direction and move very fast back to the other player.
✔ Newton’s Second Law of Motion
Explanation:
The racquet applies a force to the ball, causing it to accelerate (change speed and direction). The greater the force, the greater the acceleration. Since the ball has small mass, even a moderate force causes large acceleration — consistent with F = ma.
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4. The man pushed on the rock with a lot of force. The rock, however, was so massive that it did not move. The rock resisted the force.
✔ Newton’s First Law of Motion
Explanation:
The rock doesn’t move because it has a large mass and thus high inertia. Even though a force is applied, the rock remains at rest due to its resistance to changes in motion — this is inertia, described by Newton’s First Law.
> Note: While this could *seem* like it relates to the Second Law (since F = ma), the key point here is that
no motion occurs, emphasizing
inertia rather than acceleration. So First Law is more appropriate.
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5. Julian and Dante pulled with equal forces on the strings attached to rocks of different masses. Julian pulled on the smaller rock, it moved very quickly across the table. Dante pulled on the larger rock, it moved very slowly across the table.
✔ Newton’s Second Law of Motion
Explanation:
Both apply equal forces, but the smaller rock accelerates more because it has less mass. The larger rock accelerates less due to greater mass. This demonstrates that
acceleration is inversely proportional to mass when force is constant — exactly what Newton’s Second Law states:
a = F/m.
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✔ Final Answers:
1.
Newton’s First Law
2.
Newton’s Third Law
3.
Newton’s Second Law
4.
Newton’s First Law
5.
Newton’s Second Law
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