# Answer to Question #11721 in Mechanics | Relativity for Michelle

Question #11721

A 100g cube 2cm on each side is attached to a string and then totally submerged in water. What is the buoyant force, and what is the tension in the rope? I found the buoyant force, but I don't know how to find the tension in the rope. If you could help me that would be amazing. Thank you so much.

Expert's answer

A 100g cube 2cm on each side is attached to a string and then totally submerged in water. What is the buoyant force, and what is the tension in the rope? I found the buoyant force, but I don't know how to find the tension in the rope.

V = (0.02m)³ = 8·10^(-6) m³;

m = 0.1 kg

So, the buoyant force is

Fb = pgV = (1000 kg/m³)(9.8 m/s²)(8·10^(-6) m³) ≈ 0.0784 N

The sum of all forces acting along y-axis is equal to zero:

T + Fb - mg = 0

T = mg - Fb

So, tension of a rope is

T = (0.1 kg)(9.8 m/s²) - 0.0784 N = 0.980 N - 0.0784 N = 0.902 N.

V = (0.02m)³ = 8·10^(-6) m³;

m = 0.1 kg

So, the buoyant force is

Fb = pgV = (1000 kg/m³)(9.8 m/s²)(8·10^(-6) m³) ≈ 0.0784 N

The sum of all forces acting along y-axis is equal to zero:

T + Fb - mg = 0

T = mg - Fb

So, tension of a rope is

T = (0.1 kg)(9.8 m/s²) - 0.0784 N = 0.980 N - 0.0784 N = 0.902 N.

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