AP Physics 1 Question 198: Answer and Explanation
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8. Which one of the following statements is true concerning the motion of an ideal projectile launched at an angle of 45° to the horizontal?
- A. The acceleration vector points opposite to the velocity vector on the way up and in the same direction as the velocity vector on the way down.
- B. The speed at the top of the trajectory is zero.
- C. The object's total speed remains constant during the entire flight.
- D. The vertical speed decreases on the way up and increases on the way down.
Correct Answer: D
Since the acceleration of the projectile is always downward (because of its gravitational acceleration), the vertical speed decreases as the projectile rises and increases as the projectile falls. Choices (A), (B), and (C) are all false.