1) If we represent the distance above the ground by a positive integer and that below the ground by a negative integer,then answer the following
i) An elevator descends into a mine shaft at the rate of 4 metre per minute. What will be its position after one hour ?
ii) If it begins to descend from 10 m above the ground ,what will be its position after 40 minutes from the ground ?
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Answer:
(i) 240 metres below ground (ii) 150 metres below ground
Step-by-step explanation:
(i) Direction of the elevator= Downwards i.e. negative
Speed of the elevator= 4 metre/minute
So it's position after 1 hour =
1 hr= 60 minutes
Therefore, position after 1 hour=
Distance = Speed x Time = 4 x 60 = 240 metre
Thereby, the elevator is -240 metres above ground or 240 metres below ground
(ii) Speed = 4 metre / minute
Time = 40 minutes
Therefore, position after 40 minutes =
Distance = Speed x Time = 4 x 40 = 160
Now we have to less 160 from 10 because it is 10 metre above sea level
So the answer is -150 metres above ground or 150 metres below sea level
answer:
i)
as elevator goes down at rate of 5 metre per minute
therefore ,
Position of elevator after 1 minute = -5m
Position of elevator after 60 minutes = -5×60m
= -300m
therefore, elevator is 300m below ground level.
ii)
I THINK SO IT IS 15 M AND 45 MINS.
as elevator is 15m above the ground.
therefore initial position = +15m
now,
elevator moves down for 45 mins
distance covered in 1min. = -5m
distance covered in 45 mins = -45×5m
= -225m
therefore final position of elevator =initial position
+ distance
covered in 45
mins
= 15+(-225)
=15-225
=-210 m
therefore position after 45 mins is -210 m
that is elevator is 210m below ground level