An old coin weighs 0.315 N in air and 0.285 N when it hangs fully in water.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
An old coin weighs in air and when it hangs fully in water. Find its relative density. Silver has a relative density of and copper . Which is it more likely to be?
Need a reminder? The key ideaShow
Archimedes' principle: the buoyant force equals the weight of fluid pushed aside, . A body floats if it is less dense than the fluid, with the fraction of its volume under. Relative density .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Loss of weight. .
Step 2. Relative density. .
Answer: : it matches silver.
Check. A copper coin of the same weight would lose in water.
Watch out. Divide by the loss of weight, not by the weight in water.
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