I am so confused, water displaced by a boat

AI Thread Summary
A boat displacing 34.7 kN of fresh water will displace an equivalent weight of salt water when floating, according to Archimedes' principle. The confusion arises from the phrasing of the question, as the weight of water displaced is initially presented as a given. Participants clarify that the question aims to highlight the difference in density between fresh and salt water. The weight of the water displaced remains the same at 34.7 kN, despite the differing densities. This problem serves to reinforce understanding of buoyancy principles.
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Homework Statement



A boat floating in fresh water displaces water weighing 34.7 kN.

(a) What is the weight of the water that this boat displaces when floating in salt water of density 1.10 x 10^3 kg/m3?

Homework Equations





The Attempt at a Solution



I am utterly confused. They tell me the boat displaces a 34.7 kN weight of water, then ask for the weight of the water displaced. Looks like they gave it to me in the question?
 
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Okay, I've just been informed the weight actually refers to the boat. Answer is still in the question though. :P
 
Yes. I presume there's a part (b) that's non-trivial.
 
Ibix said:
Yes. I presume there's a part (b) that's non-trivial.

Yes, simply the difference of volume for the salt water and fresh water displaced.

I did beat the water temple in ocarina of time, I got this.
 
They give you the weight of the fresh water displaced, they want the weight of the salt water displaced. But since the weight of the water the boat displaces is equal to the weight of the boat (so long as the boat's floating) then yes, they would just be the same value.
 
Looks like a problem dedicated to Archimedes' principle.
Apparently the professor thought people would need a hint, so he added question (a)...
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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