in air an object weighs 15N when immersed in water it weighs 12N when immersed in another liquid weighs 13N. Determine the density of the object and that of the other liquid

5 answers

Its volume displaced 3 Newtons of water
3 Newtons = mass of water * g
g is about 9.81m/s^2
so mass of water =3/9.81 =0.306 kg
Water density is about 1000 kg/meter^3
0.306 kg * 10^-3m^3/kg = 3.06 *10^-4 m^3 volume
so
15 kg/3.06*10^-4 m^3 = 4.9*10^4 kg/m^3

if you want grams/cm^3
4.9*10^4 * 10^-6 m^3/cm^3 * 10^3 g/kg =49 g/cm^3
the object displaces a fixed amount of liquid

the weight of "other liquid" displaced is 2/3 of the weight of water displaced

the density of the "other liquid" is 2/3 the density of water
a. M1*g = 15 N.
M1 = 15/g = 15/9.8 = 1.53 kg = mass of object in air.
M2 = 12/9.8 = 1.22 kg = mass of object when immersed.

M1-M2 = 1,53-1.22 = 0.31 kg lost = mass of water displaced.

V*Dw = 310 g.
V*1 = 310
V = 310 cm^3 of water displaced = Vol. of object.

Vo * Do = 1530 g.
310*Do = 1530
Do = 4.94 g/cm^3. = density of object.

b. M2*g = 13 N.
M2 = 13/g = 13/9.8 = 1.33 kg = mass of object when immersed.
M1-M2 = 1.53-1.33 = 0.20 kg lost = mass of liquid displaced.

Vol. of liquid = Vo = 310 cm^3.
V*D = 200 g.
310D = 200
D = 0.645 g/cm^3. = density of liquid.
how did the1530g come about ,because am a little bit confused.
1.53 kg = 1530 g.