Three children, each of weight 356 N, make a log raft by lashing together logs of diameter 0.30 m and length 1.80 m. How many logs will be needed to keep them afloat in fresh water? Take the density of the logs to be 800 kg/m^3.(adsbygoogle = window.adsbygoogle || []).push({});

I'm interpreting this problem as a buoyancy problem for starters.

I have:

B=1068 N

V(obj)= 0.127

V(liq)= ? is this the same as the obj?

p(obj)= 800kg/m^3

p(liq)= 1.0e3 kg/m^3

I'm thinking I need to find the density of one log based on this information and divide the given density of all the logs by this. However I'm having a hard time finding a way to get to this using the equations for buoyancy. For a floating object the equation I was originally going to use was

p(liq)gV(liq)=p(obj)gV(obj) but I'm not sure what if the Volume of the liquid is the same as for the object since V is the volume of the fluid displaced from the object. Any guidance on this problem is greatly appreciated.

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# Homework Help: Buoyant force of children

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