Rain falls vertically downward with speed 20 m/s. A man runs horizontally at 15 m/s. The speed of rain relative to the man is:
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Question

Rain falls vertically downward with speed 20 m/s. A man runs horizontally at 15 m/s. The speed of rain relative to the man is:

G1 Physics · Accepted Answer

Relative velocity of rain with respect to the man is v⃗_RM = v⃗_R - v⃗_M. The horizontal component has magnitude 15 m/s and the vertical component has magnitude 20 m/s. Hence |v⃗_RM| = √(15² + 20²) = √625 = 25 m/s. Therefore option C is correct.