Long-term plan unit:

UNIT 3A: Oscillations

(Simple harmonic motion)

School:

Date:

Teacher name:

Grade:

Number present:

absent: -

Theme of the lesson

Forced oscillations. Resonance.

Uses/advantages and disadvantages of resonance

Learning objectives that are achieved at this lesson

·         Describe graphically how the amplitude of a forced oscillation changes with frequency near to the natural frequency of the system, and understand qualitatively the factors that determine the frequency response and sharpness of the resonance;

·         Show an appreciation that there are somecircumstances in which resonance is useful and other circumstances in which resonance should be avoided;

Lesson

objectives

After this lesson, students should be able to

- Describe what resonance means for a simple system of a mass on a spring. 

- Identify, through experimentation, cause and effect relationships that affect natural resonance of these systems.

- Give examples of real-world systems to which the understanding of resonance should be applied and explain why

Success

criteria

Students have achieved if they:

- Identify, through experimentation, cause and effect relationships that affect natural resonance of these systems.

- Give examples of real-world systems to which the understanding of resonance should be applied and explain why

Language

objectives

to propose hypotheses when demonstrating an experiment on hypothesis research, when describing resonance graphs.

Subject vocabulary and terminology

Oscillations, period, frequency, amplitude, displacement, velocity and acceleration of oscillations, dumping, resonance

A series of useful phrases for dialogue letters

I assume that the period of the Barton pendulum depends on ... ... ...

In the fading experiment, we will measure measurements .......

I will keep ……… constant and change ……… ..

The experiment can be improved with the help of ... ... ....

Values instilled at the lesson

Students’ achieve of specific learning objectives, and get a certain amount of knowledge, but also develop the ability to apply their knowledge in solving learning and life problems.

Cross-curricular links

Fundamentals of dynamics, especially Newton's 2 law in the form of F = ma, Hooke's law, sine and cosine graphs, angular measure (radians) and circular motion (angular velocity)

ICT skills

ICT links.https://phet.colorado.edu/en/simulation/resonance

Previous learning

Hooke’s law.

Course of the lesson

Planned stages of the lesson

Planned activities at the lesson

Resources

Beginning

5 min

5мин

1. Organizational moment.

2. Repetition, updating of knowledge. Students ask questions to each other. Score points for correct answers.  The teacher can listen to individual answers.

1. What is called mechanical vibrations? (Mechanical vibrations are the movements of the body, repeated exactly or approximately at the same time intervals.)

2. What are the main characteristics of mechanical vibrations (the Main characteristics of mechanical vibrations are: amplitude, frequency, period.)

3. What is called the amplitude of the oscillations? (Amplitude is the module of the maximum deviation from the equilibrium position.)

4. What is called the oscillation frequency? (Frequency is the number of complete oscillations per unit of time.)

5. What is called the oscillation period? (Period — the time of one complete oscillation, i.e. the minimum period of time after which the repetition occurs

Starting point

1) Millennium Footbridge. After three days the bridge was closed. Why?

2) Demonstration(any from demonstration)

·         Rubbing a wet finger around a glass; if you put different heights of liquid in the glass students should be able to hear different tones.

·         Plucking a string and varying the length of it. I use a rubber band on a tissue box, but if you have a real string instrument, the real-world context would be more obvious.

·         Blowing over a container with a small opening like a soda bottle with varying amount is liquid is nice.

Define objectives with students

Presentation

Slide 1

Slide 2

Middle

8 min

8 min

8 min

5 min

4 min

5-7 min

3. The study of new material.

Determine through conversation with students, what is forced fluctuations;

As we know, there are 4 types of oscillations (harmonic and damped; forced and free)

Let us consider an example of free oscillations of a mathematical pendulum. Under the influence of what forces is oscillatory motion? How does the amplitude of the pendulum movement change and why?

At free mechanical vibrations inevitably there is a loss of energy on overcoming forces of resistance.

What should we do to ensure that the amplitude of the pendulum does not change?

Define forced oscillation of (SHM);

Define Resonance. Driving force, natural frequency (f₀ ),

If fluctuations occur under the influence of periodic external force, such fluctuations are called forced. For example, parents shake the child on a swing, the piston moves in the cylinder of the car engine, the knife of the electric shaver and the needle of the sewing machine fluctuate.

The nature of the forced oscillations depends on the nature of the external force, its magnitude, direction, frequency of action and does not depend on the size and properties of the oscillating body.

4. Resonance. Students are provided with a text in which students should highlight the basic information: Own frequency (f0 ).  For example, the Foundation of the motor, on which it is fixed, makes forced oscillations with a frequency determined only by the number of revolutions of the motor, and does not depend on the size of the Foundation.

When the frequency of the external force and the frequency of the body's own oscillations coincide, the amplitude of the forced oscillations increases sharply. This phenomenon is called mechanical resonance.

Resonance is a sharp increase in the amplitude of forced oscillations at the same frequency of free oscillations with the frequency of the external force. In the absence of friction, the amplitude of forced vibrations at resonance should increase with the time indefinitely. In real systems, the amplitude

Video: Effects of Damping on Resonance

Group work. Determine what are the factors affecting resonance for spring system.

After studying a generalization is carried out

Resonance chart. Discuss the terms and form of the schedule . The natural frequency on the graph. Natural frequency.  Resonance graph with different attenuation.

6. The use of resonance and the fight with him. The phenomenon of resonance plays an important role in a number of natural, scientific and industrial processes. For example, it is necessary to take into account the phenomenon of resonance in the design of bridges, buildings and other structures experiencing vibration under load, otherwise under certain conditions, these structures can be destroyed. The phenomenon of resonance can cause the destruction of machines, buildings, bridges, if their natural frequencies coincide with the frequency of the periodic force. Therefore, for example, engines in cars are installed on special shock absorbers, and military units when driving on the bridge are forbidden to keep up»

Short test for assessment of understanding. Discuss with students slide 7-8

Graph of resonance. Natural frequency in the graph. Graphs of resonance for different  damping

Using resonance. Video - 2 min Glass. Building Resonance_ Structural stability during earthquakes

Solving problems.

The decision of the task individually. Verification using descriptors.

Presentation

Slide 3,4,5

https://phet.colorado.edu/en/simulation/resonance

Presentation

Hand-out

https://www.youtube.com/watch?v=uP3J_Ad2Zhw

https://www.youtube.com/watch?time_continue=6&v=iak1VuJyyoM

Worksheets CIE Paper 2 past questions

End

3-5 min

Generalization: Students will be asked if they have achieved the lesson’s objectives.

Differentiation – how do you plan to give more support? How do you plan to challenge the more able learners?

Assessment – how are you planning to check students’ learning?

Health and safety regulations

In the study of the conditions of resonance, tasks in groups-the first examines the dependence of the resonance of the stiffness of the springs of the system, the second-the mass of the oscillating system. It is possible to carry out mutual evaluation of work in groups. Differentiation by the final result in solving problems.

Evaluation of the work in the group of conditions of resonance-formative mutual evaluation through discussion of the results. When solving problems of mutual execution of the group work on the handles.

Reflection

Were the lesson objectives/learning objectives realistic? Did all learners achieve the LO?

If not, why?

Did my planned differentiation work well?

Did I stick to timings?

What changes did I make from my plan and why?

Use the space below to reflect on your lesson. Answer the most relevant questions from the box on the left about your lesson. 

Summary evaluation

What two things went really well (consider both teaching and learning)?

1:

2:

What two things would have improved the lesson (consider both teaching and learning)?

1:

2:

What have I learned from this lesson about the class orachievements/difficulties of individuals that will inform my next lesson?