n elevator descends into a mine shaft at the rate of 9m/min. If the descent startsfrom 40m above the ground level, how long will it take to reach-860m?
Answers
Step-by-step explanation:

Book a free class
Ncert solutions

Our top 5% students will be awarded a special scholarship to Lido.
Book a free class now
Set your child up for success with Lido, book a class today!
Book a free class now
Mathematics
Science

Chapters in NCERT Solutions - Mathematics, Class 7

Exercises in Integers

Question 53

Q7) An elevator descends into a mine shaft at the rate of 6 m/min. If the descent starts from 10 m above the ground level, how long will it take to reach – 350 m.
Solution
Transcript
Solution 7:
Starting position of mine shaft is = 10m above ground
but,
it moves in opposite direction so it travels the distance (-350 m ) below the ground.
Total distance covered by mine shaft = 10m - (-350m)
= 10 + 350
= 360m
Now, taken to cover a distance of 6m by it = 1 minute
Time taken to cover a distance of 1m by it = \frac{1}{6\ }\min6 1min
Therefore, tie taken to a cover a distance of 360m = \frac{1}{6}\times\ 360\ =\ 60\ \min\ \61× 360 = 60 min
60 minutes = 1 hour
thus, in one hour the mine shraft reaches = 350 below the ground