AP Physics 1 Question 423: Answer and Explanation
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1. Which of the following is a true statement regarding the motion of projectiles?
- A. The velocity of projectiles is smallest at the apex of the trajectory.
- B. All projectiles have zero velocity at the apex of the trajectory.
- C. The acceleration of projectiles is greatest at the apex of the trajectory.
- D. Projectiles have maximum kinetic energy at the apex of the trajectory.
Correct Answer: A
When a projectile reaches the top of its trajectory, the vertical component of its velocity is momentarily zero. As the horizontal velocity in standard parabolic motion is always constant, this means that the velocity of projectiles is smallest at the apex of the trajectory. Choice (A) is correct. Choice (B) is incorrect as the projectile can still have a horizontal velocity at the apex. The acceleration experienced by projectiles in flight is gravity, which is constant at all points of the trajectory. Eliminate (C). Projectiles have the smallest velocity at the apex of the trajectory, so they cannot have the maximum kinetic energy at this same point. Eliminate (D).