Water drops fall from a tap at equal time intervals. At the instant the first drop reaches the floor, the fifth drop is just leaving the tap. The tap is 20 m above the floor and g = 10 m s⁻². The height of the third drop above the floor at that instant is:
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Question

Water drops fall from a tap at equal time intervals. At the instant the first drop reaches the floor, the fifth drop is just leaving the tap. The tap is 20 m above the floor and g = 10 m s⁻². The height of the third drop above the floor at that instant is:

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G1 Physics · Accepted Answer

Time for first drop to fall 20 m is T = 2 s. Since the fifth drop is released when the first hits, four equal release intervals fit into 2 s, so interval = 0.5 s. The third drop has been falling for 1.0 s. It falls 5 m, so its height above the floor is 20 − 5 = 15 m.