A) \[3.6\,N\]
B) \[1.8\,N\]
C) \[72\,N\]
D) \[18N\]
Correct Answer: C
Solution :
At equilibrium of needle \[2TI=Mg\]. When we try to lift the needle up then force needed is equal to sum of weight of the needle and force due to surface tension on the needle i.e. \[F=Mg+2Tl=2Tl=4Tl=4\times 7.2\times 2.5\]You need to login to perform this action.
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