Kinematics

1

• Škola Gymnázium, Brno, Slovanské námestí 7
• Šablona III/2 Inovace a zkvalitnení výuky
  prostrednictvím ICT
• Název projektu Inovace výuky na GSN
  prostrednictvím ICT
• Císlo projektu CZ.1.07/1.5.00/34.0940
• Autor RNDr. Bc. Miroslav Hruška
• Tematická oblast Dynamics of particles
  (dynamika hmotných bodu)
• Název DUMu Newtons first law of motion
• Kód VY_32_INOVACE_FY.3.02
• Datum 27. 9. 2013
• Cílová skupina Žáci stredních škol s CLIL
  výukou fyziky v anglictine
• Klícová slova Dynamics, Newtons first law of
  motion, force, inertial frame of reference,
  non-inertial frame of reference, inertia,
  friction, air resistance
• Anotace Prezentace slouží k uvedení do
  problematiky prvního Newtonova pohybového zákona.
  Je vhodné ji použít pri probírání nového uciva.

2
Dynamics of particles

• 2. Newtons first law of motion

3
Newtons laws of motion

• In 1687 Isaac Newton published his three laws of
  motion (pohybové zákony)
• Newtons laws are describing the relationship
  between motion and forces
• However, Newton found out that in some frames of
  reference the laws are valid, and in some not
• 1st Newtons law belongs to Galileo!

4
Inertial and non-inertial frames

• Frames of reference where Newtons laws are valid
  are called inertial, while the others are called
  non-inertial
• The Earth, as a frame of reference, is almost
  inertial (slight differences can appear, and can
  be very important in some cases)
• http//www.youtube.com/watch?vQ0Wz5P0JdeU 633
• http//www.khanacademy.org/science/physics/forces-
  newtons-laws/newtons-laws-of-motion/v/newton-s-1st
  -law-of-motion 526

5
Newtons first law of motion

• law of inertia (zákon setrvacnosti)
• A body is at rest or in uniform rectilinear
  motion unless made to change its state by
  external forces.
• Každé teleso setrvává (persists) v klidu nebo v
  rovnomerném prímocarém pohybu, pokud není nuceno
  vnejšími silami tento svuj stav zmenit.

6
Non-inertial frames of reference

• A train speeding up
• A tram slowing down
• A car turning a curve
• Inertia is a property of matter by which it
  remains in a state of rest or continues moving
  uniformly in a straight line unless acted on by
  an external force

7
Revision

• Who formulated the laws of motion?
• How many are the laws of motion?
• What does it mean when a frame of reference is
  inertial?
• What do you know about inertiality ofa frame of
  reference connected with Earth?
• Give examples of non-inertial frames

8
Revision answers

• Isaac Newton
• Three
• Newtons laws are valid there
• Earths frame of reference is almost inertial
• A vehicle speeding up, slowing down, turning

9
Inertial frames of reference

• If there is a frame of reference at rest or in
  uniform rectilinear motion relative (with
  respect) to an inertial frame of reference, then
  it is inertial too!
• So a train going at constant velocity (at
  constant speed on a straight track) can be taken
  as an inertial frame of reference

10
Friction and air resistance

• Sometimes we think an object should keep moving
  uniformly, but it stops
• On the other hand, sometimes we expect a
  uniformly accelerated motion, and we are
  surprised that the motion becomes uniform Give
  an example
• We must take into account friction and air
  resistance!

11
No forces vs balanced forces

• If there are more forces acting on an object, and
  they are balanced (v rovnováze), i.e. their
  resultant is a zero vector, then it is the same
  situation as if there are no forces at all
• However, is it truewhen we talk about
  deformation effect?

12
Complete with proper words

• A body is at or in uniform rectilinear motion
  unless to change its by external
• is a property of matter by which it in a
  state of rest or continues moving uniformly in a
  line, unless acted on by an force
• http//www.youtube.com/watch?vM_8w-dD4RBE 49 min
  Newtons laws

13
That is all for now

• Thank you for your attention

14

• Materiál je urcen pro bezplatné používání pro
  potreby výuky a vzdelávání na všech typech škol a
  školských zarízeních. Jakékoliv další využití
  podléhá autorskému zákonu.
• Zdroje
• Bednarík, M., Široká, M. Fyzika pro gymnázia,
  Mechanika. Dotisk 3. vyd. Praha Prometheus,
  2004. 288 s. ISBN 80-7196-176-0
• Hornby, A. S. Oxford Advanced Learners
  Dictionary of Current English. 5. vyd. Oxford
  Oxford University Press, 1995. 1428 s. ISBN
  0-19-431423-5
• Autor nezarucuje funkcnost webových odkazu!