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: Rigid body and its motion Kód: VY_32_INOVACE_FY.4.07 Datum: Cílová skupina: Žáci středních škol s CLIL výukou fyziky v angličtině Klíčová slova:Rigid body, solid body, deformation, translation, rotation, moment of a force, torque, turning effect Anotace: Prezentace zavádí model tuhého tělesa a definuje moment síly vzhledem k ose otáčení.

Gravitational field and motion of bodies 7. Rigid body and its motion

3 Rigid body (tuhé těleso)  Rigid body is a model of a solid body in which deformation is neglected  Why do we use models?  Find a solid body which cannot be considered as rigid

4 Rigid body and its motion

5 Translation  At translation all points of the body have identical trajectories  All points have equal velocities  Translation can be rectilinear or curvilinear!

6 Rotation  At rotation all points of the body revolve around the same axis  All points have equal angular speeds  We are going to study rotation around a fixed ( pevné ) axis

7 Moment of a force (torque)  Moment of a force about an axis of rotation (moment síly vzhledem k ose otáčení) is the product of the force and the perpendicular distance from the line of action (vektorové přímky) of the force to the axis of rotation  cca 2 min d O

8 Torque  When a force tends to produce rotation, torque describes the turning effect of the force  The sense (smysl) of the turning effect about the axis can be clockwise or anticlockwise (counterclockwise)  Therefore moment of a force is a vector

9 Torque as a vector  The vector points according to the right-hand (-thumb) rule… d = moment arm of the force (rameno síly)

10 Moment of several forces  When several torques act on a body, the net torque or resultant torque is the sum of the individual torques  When the net torque is a zero vector, the turning effects of the forces are cancelled

11 Fill in the gaps  Rigid body is a ……… of a solid body in which deformation is ……………  Moment of a force about an ……… of rotation is the ………… of the force and the ………………… distance from the line of ……… of the force to the ……… of rotation  When a force tends to produce rotation, ……… describes the turning ………… of the force

12 Fill in the gaps - solution  Rigid body is a model of a solid body in which deformation is neglected  Moment of a force about an axis of rotation is the product of the force and the perpendicular distance from the line of action of the force to the axis of rotation  When a force tends to produce rotation, torque describes the turning effect of the force

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