A rope is wound round s drum of diameter 21cm is attached to a bucket that is resting at the bottom of a well in depth 9.89 m. Find the number of turns required to bring up the bucket such that the bottom of the bucket is suspended just above the mouth of the well

15

Step-by-step explanation:

Depth of well = No. of turns × length of one turn

Given:   Depth of well = 9.89m = 989cm          [1m = 100cm]

Let number of turns be x

Length of one turn = 2πr or π×diameter

Now , 989=x×π×21

989=x×(22/7)×21

x=989×7/(22×21)

x=14.98 ≈15 turns    

[Number of turn never be in decimals]

Hence number of  15 complete turns of the handle required to bring up the bucket

because they could drop even lower..