Answer:
502.51 kg/m^3
Explanation:
Upthrust on object in water is 40 - 20 = 20 N
Upthrust is equal to the buoyancy forces given as
B = pgv
p is density of water 1000 kg/m^3
g = acceleration due to gravity 9.81 m/s^2
v is the volume of liquid displaced.
Therefore
B = 1000 x 9.81 x v
20 = 9810v
v = 2.038x10^-3 m^3
For Upthrust in unknown liquid, we have 40 - 30 = 10 N
Bouyancy force for the liquid will be
B = P x 9.81 x 2.038x10^-3
NB- the same volume of fluid will be displaced i.e 2.038x10^-3 m^3
Equating we have
10 = P x 9.81 x 2.038x10^-3
10 = 0.0199p
p = 10/0.0199 = 502.51 kg/m^3
