A bit of a basic question: bouyancy

[matthyaouw]

(This isn't a homework question before you ask- it just came up in something I was reading.)

Am I right in thinking that a boat floating in water would float neither higher nor lower if the gravity were altered, as its mass would remain constant?
Would the same remain true if an object were resting on a solid substance that deforms plastically?

 

[Danger]

The just-off-the-top-of-my-head response would be that you're right because the water would be denser in a higher gravity field, and thus offer more resistance to being displaced. I'm really not sure, though.

 

[Doc Al]

Am I right in thinking that a boat floating in water would float neither higher nor lower if the gravity were altered, as its mass would remain constant?

That's correct. For an object to float, the buoyant force (the weight of displaced water, which equals \rho V_{(disp)} g) must equal the weight of the object (mg). The volume of water displaced does not depend on the strength of gravity.

Would the same remain true if an object were resting on a solid substance that deforms plastically?

No.

 

[matthyaouw]

Thanks for your help.