Fig. 4.1 shows a long vertical tube, sealed at the base and open at the other end. The tube is 1.0m long. The cross-sectional area of the tube is 4.0 × 10⁻⁴m². It is filled with a liquid of density 1.4 × 10⁴kg/m³. [Figure 4.1] The atmospheric pressure is 1.0 × 10⁵ Pa.

1. (a)(i)Calculate: the total pressure in the liquid at the bottom of the tube total pressure = .......................... Pa[3]
2. (a)(ii)the force exerted on the inside surface of the bottom of the tube. force = .......................... N[2]
3. (b)(i)A small sheet of glass is placed over the open end of the tube. The tube is inverted in a container of the dense liquid. The open end of the tube and the sheet of glass are a short distance below the surface of the liquid. Fig. 4.2 shows the arrangement. [Figure 4.2] The sheet of glass seals the open end of the inverted tube. Describe what happens in the inverted tube when the sheet of glass is removed.[3]
4. (b)(ii)This equipment is used to make a measurement that is used to calculate atmospheric pressure. Describe the measurement made and then used in the calculation of atmospheric pressure. You may draw a diagram to help your description.[2]

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