Question

An elevator descends into a mine shaft at the rate of 4 metre per minute.What will be its position after one hour? If it begins to descend from 10m above the ground, what will be its position after 40 minutes

Answer 1

Rate = 4m/min

Find the distance traveled below ground in an hour

1 min = 4m

60 mins = 4 x 60 = 240 m

Answer: The shaft will be 240 m below ground after an hour.

Find the distance traveled in 40 mins:

1 min = 4m

40 min = 4 x 40 = 160 m

Find the relative distance of the shaft after 40 mins:

Given that it started from 10m above ground

Distance = 10 - 160 = -150m

Answer: It will be 150m below ground after 40 mins

Answer 2

The speed is going down with speed 4m in one minute. so in 1 hour , or 60 minutes it will descend to the depth 4×60 =240m.

Its position will be -240m from the ground.


If the lift descends from 10m above the ground , its initial position will be +10m.

So in 40 min , the depth covered =4×40=160m.

So the lift goes -160m from initial position.

Its position from ground will
-160+10=-150m