A person with a mass of 74 kg and a volume of 0.079 m3 floats quietly in water.
(a) What is the volume (m^3) of the person that is above water?
(b) If an upward force F is applied to the person by a friend, the volume of the person above water increases by 0.0019 m3. Find the force F (N).

Question

A person with a mass of 74 kg and a volume of 0.079 m3 floats quietly in water.
(a) What is the volume (m^3) of the person that is above water? 
(b) If an upward force F is applied to the person by a friend, the volume of the person above water increases by 0.0019 m3. Find the force F (N).

anonymous · Answer

It should be the same, equal and opposite.  I think...

anonymous · Answer

So .079 and then .0809

anonymous · Answer

Person floats when the volume of water displaced has a weight equal to his own. 74kg person displaces 0.074m3 of water, thus 0.079m3-0.074m3=0.005m3 is above water. 

The friend must supply the weight of water no longer displaced. 0.0019m3 of water has a mass of 1.9kg, which corresponds to (9.8N/kg)(1.9)=18.6N.

anonymous · Answer

That sounds better than mine....

anonymous · Answer

Thank you very much!