Question
A thin flat circular disc of radius 4.5 cm is placed gently over the surface of water. If surface tension of water is 0.07 ~N ~m ^ -1 , then the excess force required to take it away from the surface is
NEET
Physics
Mechanical Properties of Fluids
2024
NEET 2024
NEET Physics Question (2024) — Solution
Options
- A. 198 N
- B. 1.98 mN
- C. 99 N
- D. 19.8 mN
Answer
D. 19.8 mN
Step-by-step solution
aligned & Excess force =T 2 R \\ & = 7 100 2 3.14 4.5 100 \\ & =197.82 10^ -4 \\ & =19.8 10^ -3 ~N \\ & =19.8 mN aligned
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