# Explain why a ball thrown horizontally from the top of a cliff and a ball dropped vertically from the same point at the same instant will reach the ground at the same time, despite the thrown ball travelling a greater total distance.

> IB DP Physics Standard Level (2023 syllabus) — A.1 Kinematics · Explain · 4 marks

## Mark scheme (4 marks)

1. The horizontal and vertical motions of the thrown ball are independent of each other.
2. Both balls experience the same downward acceleration due to gravity (g) in the vertical direction.
3. Both balls start with zero vertical velocity, so they undergo identical vertical motion.
4. Because the vertical motion is identical for both balls, they take the same time to fall the same vertical height, regardless of the horizontal distance covered.

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- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
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