A multistorey building has 25 floors above ground (each 5 m) and 3 basement floors (each 5 m). A lift moves at 1 m/s. If a man starts from 50 m above ground, how long to reach the 2nd basement floor?
60 seconds (1 minute)
2nd basement is 10 m below ground (−10 m). Distance from +50 m to −10 m is 60 m → 60 s.