Q21 of 81 Page 273

Find the ratio of the weights, as measured by a spring balance, of a 1 kg block of iron and a 1 kg block of wood. Density of iron = 7800 kg m-3, density of wood = 800 kg m-3 and density of air = 1293 kg m-3.

Given, Density of iron, ,

density of wood,


density of air


The objects can be thought of as fully immersed in air. Therefore, there will be a buoyant force working upwards.


Let mass of iron be and that of wood be . Let there volumes be and respectively.


The weight of iron block becomes, —————(1)


Similarly, weight of wooden block is —————(2)


Taking ratio of (1) and (2)



(ANS)


More from this chapter

All 81 →
19

A hollow spherical body of inner and outer radii 6 cm and 8 cm respectively floats half-submerged in water. Find the density of the material of the sphere.

 20

A solid sphere of radius 5 cm floats in water. If a maximum load of 0.1 kg can be put on it without wetting the load, find the specific gravity of the material of the sphere.

 22

A cylindrical object of outer diameter 20 cm and mass 2 kg floats in water with its axis vertical. 1f it is slightly depressed and then released, find the time period of the resulting simple harmonic motion of the object.

 23

A cylindrical object of outer diameter 10 cm, height 20 cm and density 8000 kg m-3 is supported by a vertical spring and is half dipped in water as shown in figure(13-E6). (a) Find the elongation of the spring in equilibrium condition. (b) 1f the object is slightly depressed and released, find the time period of resulting oscillations of the object. The spring constant =500 N m-1.