A piece of metal of volume 250 cetimetre cube floats in water when 85 percent of it's volume is under water.Calculate the upthrust on the metal.

Question

250*85=21250

Answer 1

well, 250*0.85 = 212.5 cm^3
so it displaces
212.5 grams of water assuming water has density of 1 gram/cm^3

If your book does force in grams, that is the answer.
However that 212.5 grams is really the MASS of water displaced. To get the force up you really should multiply that by g, the acceleration of gravity which would give you force in dynes. g = 981 cm/s^2 on earth approximately

Answer 2

This is the second question in a row which confused mass and weight or force. Are you using the same old physics book I wonder?

Answer 3

Our spring scales would not work on the moon correctly. We would have to multiply the measurement in grams or kilograms by 6 to get the right answer :)
On the other hand a balance scale would work fine.

Answer 4

Surely one can't have a book that old, the binding would be brittle.