A wooden stick 2m long is floating on the surface of water. The surface tension of water 0.07 N/m. By putting soap solution on one side of the sticks the surface tension is reduced to 0.06 N/m. The net force on the stick will be

Options

A. `0.06`N
B. `0.01`N
C. `0.02`N
D. `0.07`N

Answer

C

Explanation

By definition ,`T = F/l or F = Tl`
Generally for a homogeneous liquid we use 2l, because of the finite width of stick .But in this case, the liquid on the two sides of the stick (water and soap solution ) are different
` :. ` Net force on the stick ` = F_(1) -F_(2)`
` :. F_(1)-F_(2) =(T_(1)-T_(2))l = (0.07-0.06) xx2 `
` :. F_(1)-F_(2) = 0.01 xx 2 = 0.02 `