A packet weighs 40kg in air but when it is totally submerged into a 1mx1m square tank the weight of the packet is only 18kg. How much does the water rise in the tank?

water rise = 22 mm

Explanation:

weight of packet IN AIR = 40 * 9.81 = 392.4 N

weight of packet IN WATER = 18 * 9.81 = 176.58 N

by Archimedi's principle

difference in weight = weight of displaced water

w_a - w_w = / rho_w v_d g

392.4 - 176.58 = 1000 * v_d * 9.81

v_d = 0.022 m^3

v_d = A*H_rise

0.022 = 1*H_rise

H_rise = 0.022 m = 22 mm

water rise = 22 mm