1 Škola: Gymnázium, Brno, Slovanské náměstí 7 Šablona: III/2 – Inovace a zkvalitnění výuky prostřednictvím ICT Název projektu: Inovace výuky na GSN prostřednictvím ICT Číslo projektu: CZ.1.07/1.5.00/ Autor: RNDr. Bc. Miroslav Hruška Tematická oblast: Gravitational field and motion of bodies (gravitační pole a pohyb těles) Název DUMu: Hydrostatics – revision Kód: VY_32_INOVACE_FY.4.17 Datum: Cílová skupina: Žáci středních škol s CLIL výukou fyziky v angličtině Klíčová slova:Hydrostatics, hydrostatic pressure, Pascal’s law, Archimedes’ principle Anotace: Prezentace procvičuje principy Pascalova a Archimedova zákona

Gravitational field and motion of bodies 17. Hydrostatics – revision

3 Hydrostatics Which law deals with pressure, and which with force?

4  The cause of the ……………. in a fluid can be: an ……………… force acting on the fluid the forces of ………… acting on individual …………….. of the fluid  The pressure ………… by an ………….. force acting on a liquid in a closed ……………… is at all ………. of the liquid the same Fill in the gaps I

5  The cause of the pressure in a fluid can be: an external force acting on the fluid the forces of gravity acting on individual particles of the fluid  The pressure caused by an external force acting on a liquid in a closed container is at all points of the liquid the same Fill in the gaps I – solution

6 Exercise I  A force of 10 N acts on the small piston of a hydraulic device of radius 2 cm. The large piston has got a radius of 20 cm. Find the magnitude of the force acting on the large piston?  F 1 = 10 N, r 1 = 2 cm, r 2 = 20 cm  F 2 = ?

7 Solution I  The area of the small piston is S 1 = π × 2 2 cm 2  The area of the large piston is S 2 = π × 20 2 cm 2  The force acting on the large piston is N

8  We refer to the …………… caused by the forces of …………… acting on individual particles of a liquid as the ……………… pressure  Any object ………………. in a liquid is …………… up by a force equal to the ………… of the liquid …………… by the object Fill in the gaps II

9  We refer to the pressure caused by the forces of gravity acting on individual particles of a liquid as the hydrostatic pressure  Any object immersed in a liquid is buoyed up by a force equal to the weight of the liquid displaced by the object Fill in the gaps II – solution

10 Exercise II  Find the hydrostatic pressure in water at a depth of 5 m.  h = 5 m, ρ = 1000 kg/m 3, g = 10 m/s  p h = ?  p h = hρg = 5 × 1000 × 10 Pa = 50 kPa The hydrostatic pressure is 50 kPa.

11  Find the net force acting on an iron cube of volume 100 cm 3 completely immersed in water (ρ t = 7860 kg/m 3 ).  The buoyant force F vz  The force of gravity F G Exercise III

12  V = 100 cm 3 = m 3  ρ T = 7860 kg/m 3  g = 10 m/s 2  ρ k = 1000 kg/m 3  The buoyant force F vz  The force of gravity F G Solution III Since ρ T > ρ k, F = F G – F vz = 7.86 N – 1.00 N = 6.86 N

That is all for now Thank you for your attention

14  Materiál je určen pro bezplatné používání pro potřeby výuky a vzdělávání na všech typech škol a školských zařízeních. Jakékoliv další využití podléhá autorskému zákonu. Zdroje:  Bednařík, M., Široká, M. Fyzika pro gymnázia, Mechanika. Dotisk 3. vyd. Praha: Prometheus, s. ISBN  Hornby, A. S. Oxford Advanced Learner’s Dictionary of Current English. 5. vyd. Oxford: Oxford University Press, s. ISBN