Question

An elevator descends into a shaft at the rate of 3m/min. If the descent
starts from 40m above the ground level, how long will it take to reach -20m?

Answer 1

20 mins
3 metre is decended in 1min
then 60 m is descended in
$\frac{1 \times 60}{3 } min$
=20 min

Answer 2

The time taken to reach -20m is 20min.

Given:-

Rate of descent of shaft = 3m/min

Height above the ground = 40m

Height below the ground = -20m

To Find:-

The time taken to reach -20m.

Solution:-

We can easily calculate the time taken to reach -20m by using the following procedure.

As

Rate of descent of shaft (v) = 3m/min

Height above the ground = 40m

Height below the ground = -20m

Time required (t) =?

Here,

The total distance covered (s) = 40 + 20 = 60m

According to the formula,

$speed = \frac{distance}{time}$

$time = \frac{distance}{speed}$

$t = \frac{s}{v}$

$t = \frac{60}{3}$

$t = 20min$

Hence, The time taken to reach -20m is 20min.

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