Physics practical Ch3 Q15 and Q16

Practice Question Solving
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Hi, regards this type of questions, I saw the solution as
Force = Weight = mass * gravitational acceleration, therefore 14494N in Q15.

The answer is 11660N, 1470N respectively, can someone explain how to solve this question?

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Hey, you have to calculate the Buoyant force
Fb= ρgV
density of water is 1kg/dm^3
so, Fb=1 * 9.8 * 340
=3332N
Weight(F)=mg=1530 * 9.8=14994N
Net force= 14994-3332=11662 N
I think 11660 is an approximate value of this.
Correct me if there’s any mistakes…

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@Elvina_Erin
Isn’t the volume 340 in dm3?
Don’t we have to change it to m3?

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Hey, yes it is generally taken in m^3. But I took the density of water in kg/dm^3 so I didn’t change it for Volume. If you’re taking it in m^3 you should change the density of water to kg/m3. Make sure the units match.

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Oh is this because density of water = 1000kg/m3 = 1kg/dm3?

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Exactly… so ,Fb=1000kg/m^3 * 9.8 * 0.34m^3 = 3332N

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Ahh Yeah, Sorry my bad.
Didn’t check the density value clearly.

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