Question

A 1.2 kg block of wood (density of wood 0.6g/cc) is floating in water of density 1.1 g/cc. If a metal block of mass 1.2 kg is tied to the wooden block, the combination sinks. What must be the minimum density of the metal?

Answer 1

Answer:

let the weight of metal needed be m

volume of metal =m/14

Weight of wood =12kg

volume of wood =12/0.6=20

Total volume =20+m/14

Now, Weight = buoyant force

The volume displaced will be of only of wood:

=> (m+12)g=g(0.9×20)

=> m = 6 Kg

b) Now, Weight = buoyant force

The volume displaced will be of wood and metal:

(m+12)g=(0.9×20+14m)g

=> m=6.46Kg=6.5 Kg (approximately)