Question

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

• A. $40$ minutes
• B. $50$ minutes
• C. $60$ minutes
• D. $70$ minutes

Answer 1

The correct option is C $60$ minutes

Distance descended is denoted by a negative integer,

Initial height $=+10m$

Final Depth $=-350m$

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

Given, the time is taken by the elevator to descend $-6m=1minute$

Thus, time taken by the elevator to descend $-360m=\frac{(-360)}{(-6)}$ ------- [from the formula : $speed=\frac{distance}{time}$]

$=60minutes$