Work done on moving a submerged object

[Murray Inglis]

Homework Statement

A 5.00 kg air-filled, sealed, rigid float tank that has a volume of 1.00 m3
is pulled 50.4 m
down to the seafloor in order to assist in lifting a sunken object. A diver standing on the
seafloor cranks a winch to pull the tank down.
How much work is required to pull the tank down? (You may safely ignore the mass
in the air tank and the mass of the winch rope.)

Relevant Equations

Fb = p(rho)Vg

I first worked out the buoyant force using rho = 1000, g = 9.8 and V = 1. (this gives Fb = 9800)
I then worked out Fg of the tank (5 x 9.8 = 49)
Then I used Fnet = Fb - Fg - T = 0 to work out tension as 9751.
I thought the work done would be the work done by tension (9751 x 50.4), but I'm not sure if this works.

 

[Doc Al]

I thought the work done would be the work done by tension (9751 x 50.4), but I'm not sure if this works.

Sounds good to me.

 

[Murray Inglis]

Sounds good to me.

Oh great, thanks. It was a 7 mark question so it just felt like I was missing something.

 

[kuruman]

Oh great, thanks. It was a 7 mark question so it just felt like I was missing something.

You are missing the units next to the numbers you provided. If I were scoring this, I would subtract at least 1 mark for this.