Advertisements
Advertisements
Question
A body of mass 70 kg, when completely immersed in water, displaces 20,000 cm3 of water. Find: (i) The weight of body in water and (ii) The relative density of material of the body.
Advertisements
Solution
Weight of body = 70 kg
Volume of water displaced by body = 20,000 cm3 = 0.02 m3
(i) Mass of solid immersed in water = mass of water displaced
Mass of solid immersed in water = Density of water × Volume of water displaced
Mass of solid immersed in water = 1000 × 0.02 = 20 kg
Weight of the body, W=mg
Weight of the body in water =(70×9.8)−(20×9.8)=50 kgf
(ii) R.D. of solid = Density in C.G.S. (without unit)
Density in C.G.S. = `"mass"/"volume" = (70 xx 1000)/(20,000) = 3.5` gcm3
R.D. = 3.5
APPEARS IN
RELATED QUESTIONS
A sphere of iron and another of wood, both of same radius are placed on the surface of water. State which of the two will sink? Give a reason for your answer.
How does the density of material of a body determine whether it will float or sink in water?
A solid of density 5000 kg m-3 weighs 0.5 kgf in air. It is completely immersed in water of density 1000 kg m-3. Calculate the apparent weight of the solid in water.
A metal cube of edge 5 cm and density 9 g cm-3 is suspended by a thread so as to be completely immersed in a liquid of density 1.2 g cm-3. Find the tension in thread. (Take g = 10 m s-2)
Relative density of a substance is expressed by comparing the density of that substance with the density of :
A solid weighs 1.5 kgf in air and 0.9 kgf in a liquid of density 1.2 × 103 kg m-3. Calculate R. D. of solid.
A solid weighs 32 gf in air and 28.8 gf in water. Find: (i) The volume of solid, (ii) R.D. of solid and (iii) The weight of solid in a liquid of density 0.9 g cm-3.
A body of volume 100 cm3 weighs 1 kgf in air. Find:
- Its weight in water and
- Its relative density.
A solid of area of cross-section 0.004 m2 and length 0.60 m is completely immersed in water of density 1000 kgm3. Calculate:
- Wt of solid in SI system
- Upthrust acting on the solid in SI system.
- Apparent weight of solid in water.
- Apparent weight of solid in brine solution of density 1050 kgm3.
[Take g = 10 N/kg; Density of solid = 7200 kgm3]
