A lift moves upward at constant speed 5 m s⁻¹. A passenger throws a ball vertically upward at 15 m s⁻¹ relative to the lift. Taking g = 10 m s⁻², the maximum separation between the ball and the lift is:
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Question

A lift moves upward at constant speed 5 m s⁻¹. A passenger throws a ball vertically upward at 15 m s⁻¹ relative to the lift. Taking g = 10 m s⁻², the maximum separation between the ball and the lift is:

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G1 Physics · Accepted Answer

Relative to the lift, the ball has initial upward velocity 15 m s⁻¹ and relative acceleration −g. At maximum separation, relative velocity becomes zero. Hence 0 = 15² − 2(10)h, giving h = 11.25 m.