How Does Immersion Affect Spring Scale Readings?

[jenha14]

A 10.5 kg block of metal measuring 12 cm 10 cm 10 cm is suspended from a scale and immersed in water. The 12.0 cm dimension is vertical and the top of the block is 5.25 cm below the surface of the water.
(a) What are the forces acting on the top and on the bottom of the block? (Use P0 = 1.0130 105 N/m2.)
(b) What is the reading of the spring scale?

ATTEMPT AT SOLUTION
(a) The forces acting on the top of the block is:
(0.1m)*(0.1m)*(P0+1000*9.8*0.0525 N/m^2)
= (1.0130e3+5.1)N = 1.0181e3 N
and on the bottom of the block is:
(0.1m)*(0.1m)*(P0+1000*9.8*0.1725 N/m^2)
= (1.0130e3+16.9)N = 1.0299e3 N

(b) I'm stuck on this one

 

[wysard]

(b) The block displaces the mass of the water that would have taken that space. Start there.

 

[ogb p]

. I know the reading on the spring scale would be the weight of the block, which is 10.5 kg * 9.8 m/s^2 = 102.9 N, but I'm not sure how to incorporate the immersion in water to calculate the reading. I would need to know the density of the metal block to calculate its buoyancy force, but that information is not provided. Without that information, I cannot accurately determine the reading of the spring scale.