Final answer:
Projectile motion is showcased by an object moving in a curved trajectory under the influence of gravity. The best example among the options is a person throwing a rock. The other choices do not illustrate projectile motion as they involve different forms of movement.
Explanation:
Understanding Projectile Motion
Projectile motion refers to the motion of an object that is thrown into the air and is affected only by the forces of gravity and air resistance. This type of motion follows a curved trajectory known as a parabola. Among the options provided, the best example of projectile motion is:
- A person throwing a rock: This scenario exemplifies projectile motion because the rock travels through the air in a curved path until it hits the ground due to the force of gravity.
In contrast, the other options do not demonstrate projectile motion because:
- An athlete running on a track involves linear motion, not a curved trajectory.
- A child swinging on a swing set has a motion that involves circular paths influenced by tension and gravity, rather than pure projectile motion.
- A teacher picking up a pencil is a stationary action and does not involve any projectile movement.
Therefore, the correct answer to the question is that a person throwing a rock is the example of projectile motion.
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