A rectangular frame having dimensions of `5 cm xx 3 cm xx 3 mm` is placed vertical in such a way that its longest side just touches the water surface. What will be the downward force acting on the frame? Surface tension of water is 0.72 `Nm^(-1)`.

Explanation

T=surface tension
Force `=T xx 2 ("length+ thickness")`
`=0.072 xx 2(5 xx 10^(-2) +3 xx 10^(-3))`
`=0.144 (0.05+0.003)`
`=0.007 or 7 xx 10^(-3)N`