1. An additional force of 0.212 N was required to keep a cylinder of 150 mm OD with weight equal to the buoyant forces, floating in a liquid with contact angle β = 60° due to surface tension effects....

1. An additional force of 0.212 N was required to keep a cylinder of 150 mm OD with weight equal to the buoyant forces, floating in a liquid with contact angle β = 60° due to surface tension effects. Determine the value of surface tension. (0.45 N/m)

2. Show that the capillary rise in an annulus is given by 2σ cos β/γ (r_o
– r_i
), where r_o
and r_i
are the radii and σ is the surface tension, γ is the specific weight and β is the contact angle.