Question

An elevator descends into a mine shaft at the rate of 15 m/min. If the descend starts from 10 m above the ground level, how long will it take to reach -140 m.

• A. 18 minutes
• B. 10 minutes
• C. 38 minutes
• D. 8 minutes

Answer 1

The correct option is B

10 minutes

Initial position of the elevator is 10 m above the gorund.
The elevator has to reach -140 m.
So, the elevator will have to descend 150 m in total to reach -140 m.
Given that the lift descends at the rate of 15 m/minute.
$\Rightarrow$ To decend 15 m $\to$ elevator takes 1 minute
$\Rightarrow$ To decend 150 m $\to$ elevator takes $\frac{150}{15}$= 10 minutes
$\therefore$ The elevator will take 10 minutes.