A crown has a weight of 8.84 N in air. You dunk it under some water and it's apparent weight is 6.86 N. What is the density of the crown? The density water = 1000 kg/m3
A.4500 kg/m3
B.9000 kg/m3
C.3300 kg/m3
D.7300 kg/m3
Up thrust from water = 8.84 - 6.86 = 1.98N
Upthrust = volume displaced*water density*g, so volume displaced = 1.98/(1000*10) m^3. (again using g = 10m/s^2) → 0.000198m^3
volume displaced = volume of crown, so
density of crown = mass of crown/volume of crown → (8.84/10)kg/0.000198m^3 → 4464 kg/m^3
Nearest supplied answer is A.