A sealed instrument capsule is being tested inside a vessel from which nearly all the air has been removed.
The pressure inside the capsule is 90 000 Pa90\,000\ \text{Pa}90000 Pa and the pressure surrounding it is zero. A flat access hatch covers an opening of area 0.016 m2.
Explain why the hatch must be secured to keep the capsule sealed.
Calculate the magnitude of the resultant pressure force acting on the access hatch.
During a later test, the pressure inside the capsule is lowered to 75 000 Pa75\,000\ \text{Pa}75000 Pa while the pressure surrounding the capsule remains zero.
The hatch fasteners can provide a maximum inward restraining force of 1250 N.
Explain whether the fasteners keep the hatch in place during this test.
Your answer should include a calculation.
132 exam-style questions on Edexcel GCSE Physics 15.2 Pressure in fluids, covering 15.2.1 Atmospheric pressure and height, 15.2.2 Pressure in fluids, 15.2.3 Pressure, force and area, 15.2.4 Pressure and depth, 15.2.5 Pressure in liquids: depth and density, 15.2.6 Upthrust, and 15.2.7 Floating and sinking. Each one has a worked solution and a mark scheme showing where the marks go.