The density of water is 1.0 g/cm³. The density of the oil in the left column of the U-tube shown below is: A) 0.20 g/cm³ B) 0.80 g/cm³ C) 1.0 g/cm³ D) 1.3 g/cm³ E) 5.0 g/cm³

Question

Quizplus · Accepted Answer

Since the U-tube is balanced, the pressure at points A and B must be equal. Thus, the weight of the water in the left column must be equal to the weight of the oil in the right column. We know that the density of water is 1.0 g/cm^3. Let x be the density of the oil in the right column. Then, the weight of the oil column is (12 cm)*x*(1 cm^2)*g, where g is the acceleration due to gravity. The weight of the water column is (8 cm)*(1.0 g/cm^3)*(1 cm^2)*g. Since these weights are equal, we have:

(12 cm)*x*(1 cm^2)*g = (8 cm)*(1.0 g/cm^3)*(1 cm^2)*g
x = (8 cm)/(12 cm) * (1.0 g/cm^3) = 0.67 g/cm^3

This value is closest to option B, which is 0.80 g/cm^3.

The Density of Water Is 1