A cylindrical metal can with a radius of 4.25 cm is floating upright in water. A rock is placed in the can, causing it to sink 0.0234 m deeper into the water. What is the weight of the rock?

additional volume of water displaced = .0234 * pi * .0425^2 = 1.33*10^-4 m^3

density of water = 1000 kg/m^3 approx
so
mass of rock = 1.33*10^-1 Kg
weight of rock = m g = 9.81*.133 = 1.3 Newtons