Question

An elevator descends into a mine shaft at the rate of 6 m/min. If the descend starts from 10 m above the ground level, how long it will take to reach the shaft 350 m below the ground level?

Answer 1

Distance descended is denoted by a negative integer.

Initial height = +10 m

Final depth = −350 m

Total distance to be descended by the elevator = (−350) − (+10) = −360 m

Time taken by the elevator to descend −6 m = 1 min

Thus, time taken by the elevator to descend −360 m = (−360) ÷ (−6)

= 60 minutes = 1 hour