A U-tube is open to the atmosphere at both ends. Water is poured into the tube until the water rises part-way along the straight sides, and then some oil with a density of 920 kg/m³ is poured into one end. This causes the water surface on that side of the tube to go down by 5.50 mm and the surface on the other side to go up by the same amount. How much higher is the top surface of the oil on that side of the tube compared with the surface of the water on the other side of the tube? A) 0.96 mm B) 1.2 mm C) 0.44 mm D) 1.2 cm E) 1.1 cm

Question

Quizplus · Accepted Answer

The pressure at the bottom of the U-tube is the same on both sides. The pressure due to the water is the same on both sides. The pressure due to the oil is greater on the side with the oil. The difference in pressure is due to the difference in height of the oil and water. The difference in height is 5.50 mm. The density of the oil is 920 kg/m³. The pressure due to the oil is 920 kg/m³ * 9.81 m/s² * 5.50 mm = 51.8 Pa. The difference in height of the oil and water is 51.8 Pa / (920 kg/m³ * 9.81 m/s²) = 0.96 mm.

A U-Tube Is Open to the Atmosphere at Both Ends