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Question
The length of a needle floating on water is 2 cm. The additional force due to surface tension required to pull the needle out of water will be (S.T. of water = 7.0 × 10−2 N/m).
Options
32 × 10−4 N
28 × 10−4 N
24 × 10−4 N
20 × 10−4 N
MCQ
Solution
28 × 10−4 N
Explanation:
T = `"Force"/(2"l")`
Force = 2Tl
= 2 × 7 × 10−2 × 2 × 10−2
= 28 × 10−4 N
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