A helicopter rises vertically from rest with constant acceleration g. A food packet is dropped when the helicopter is at height h. The time taken by the packet to reach the ground is closest to:
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A helicopter rises vertically from rest with constant acceleration g. A food packet is dropped when the helicopter is at height h. The time taken by the packet to reach the ground is closest to:

G1 Physics · Accepted Answer

The helicopter starts from rest with upward acceleration g. At height h, v²=2gh, so packet release speed is √(2gh) upward. For the packet: 0=h+√(2gh)t-gt²/2. Let τ=t√(g/h): 1+√2τ-τ²/2=0, giving τ=√2+2≈3.4. Thus t≈3.4√(h/g), option A.