Question

A piece of wood of uniform cross section and height 15 cm floats vertically with its height 10 cm in water and 12 cm in spirit. Find the density of
(i) wood and (ii) spirit.

Answer 1

Answer:

Explanation:Using Arhcimede's principle ,

In case of water ,weight of water displaced = weight of wood  

  ρ  

w

​

v  

w

​

g=ρ  

l

​

v  

(woodinwater)

​

g

  this gives ρ  

w

​

15Ag=1×10Ag here , density of liquid (water )=1g/cc, A= base area

this gives,  ρ  

w

​

=10/15=2/3=0.67g/cc

for spirit ,  

ρ  

w

​

v  

w

​

g=ρ  

s

​

v  

(woodinspirit)

​

g

this gives,  ρ  

w

​

15Ag=ρ  

s

​

×12Ag

this gives ρ  

s

​

=ρ  

w

​

×  

12

15

​

=2/3×5/4=10/12=0.83g/cc