IB Physics SL B.3.1 Pressure

Practise calculating pressure from perpendicular force and area, using pressure differences to find net forces and deriving hydrostatic or buoyant effects from depth and density.

Exam points

calculate P = F/A using perpendicular force and area converted correctly into square metres
find net force from a pressure difference times area, including atmospheric pressure on one side
derive or apply ΔP = ρgΔh and connect lower-fluid pressure to an upward buoyant resultant

[Maximum number: 2]

A solid cylinder of height h and density $\rho$ rests on a flat surface.

Figure for Question B.3.1—Pressure question 1 — IB Physics SL

Show that the pressure $p_{\mathrm{C}}$ exerted by the cylinder on the surface is given by $p_{\mathrm{C}}=\rho g h$ .

weight of cylinder $=A h g \rho$ $\text { pressure }=\frac{F}{A}=\frac{A h g \rho}{A}$

Marking guidance:

Allow use of $A=\pi r^{2}$ in MP1.

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B.3.1—Pressure question 1