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 sphere of wood of the same radius are held under water. Compare the upthrust on the two spheres.
[Hint: Both have equal volume inside the water].
Complete the following sentence.
Density in kg m-3 = ............ × density in g cm-3
A body weighs W1gf in air and when immersed in a liquid it weighs W2gf, while it weights W3gf on immersing it in water. Find:
- volume of the body
- upthrust due to liquid
- relative density of the solid
- relative density of the liquid
Calculate the mass of a body whose volume is 2 m3 and relative density is 0.52.
A body weighs 20 gf in air and 18.0 gf in water. Calculate the relative density of the material of the body.
A solid weighs 120 gf in air and and 105 gf when it is completely immersed in water. Calculate the relative density of solid.
A stone of density 3000 kgm3 is lying submerged in water of density 1000 kgm3. If the mass of stone in air is 150 kg, calculate the force required to lift the stone. [g = 10 ms2]
A solid of R.D. 4.2 is found to weigh 0.200 kgf in air. Find its apparent weight in water.
A cylinder made of copper and aluminium floats in mercury of density 13.6 gem-3, such that 0.26th part of it is below mercury. Find the density of solid.
