Heat engines, 26 lesson

Long-term plan unit: 

School:

Date:

Teacher name:

Grade: 10 Physics

Number present:

absent:

Theme of the lesson

Heat engines.

Learning objectives(s) that this lesson is contributing to

10.2.3.2 – to describe the operating principle and application of the heat engine.

Lesson objectives

- to study the principle of operation of the heat engine;

- to study of determining the efficiency of a heat engine;

-to be able to solve problems about topic.

Evaluation criteria

A student has achieved a learning goal if ...

  - knows the principle of operation of the heat engine, determining the efficiency of the heat engine;

    - describes the principle of operation of a heat engine, applies the formula for calculating the efficiency of a heat engine when solving problems;

Language Objectives

Subject-Specific Vocabulary and Terminology:

Hot Body (source of heat), Cold Body (absorbs heat). Efficiency of an engine.

Useful Sets of Phrases for Dialogue and Writing:

Heat engines – transfer heat from hot reservoir to cold reservoir. It converts some of the thermal energy into work.

Previous learning

Introduction to thermodynamics

Course of the lesson

Planned timings

Planned activities at the lesson

Resources

Beginning

3 min

1 min

10 min

Checking Homework

(T, W) Organizational moment (announcement of the topic, objectives and goals of the lesson, psychological preparation of students for the lesson).

Task. Actualization of needed knowledge

Aim: adjust students to study, repeat the terminology on this topic for a deeper understanding of the studying material.

Problem situation: “Using internal energy means to do useful work at the expense of it, for example, to lift a load, to transport wagons and etc. And this, in turn, means that the internal energy must be converted into mechanical energy. In the 3rd century BC, the great Greek mathematician and mechanic Archimedes built a cannon that fired with steam.”

Experiment: "The transformation of gas energy into mechanical energy."

Class is divided into 2 groups, each group receives instruments and materials. It is necessary, using devices, create a device that can do the work and make a conclusion.

Instruments and materials: a tripod, a test tube, a cork, a glass of water, a spirit lamp.

Questions:

1. How to do it with the help of instruments and materials that you have?

(Which group will quickly collect the scheme of experience, according to the instruments and materials.)

2. What will we observe?

Conclusion of experiment: When water is heated in a tube that is closed by a stopper, the amount of steam under the stopper increases and its pressure on the stopper increases. Finally, the steam pressure pushes the cork out while the steam does the work. Part of the original energy of the steam went into doing the work of pushing the cork. The internal energy of steam has turned into mechanical energy. Since the steam is still quite hot, it gives up the remaining energy to the surrounding air, which has a lower temperature.

Teacher’s action: ask some question, organize an experiment work in groups.

Student’s action: students are divided in 2 groups,  they work together, answer for teacher’s questions and conduct the experiment and make a conclusion..

Feedback: teacher-student, student-student

A tripod, a test tube, a cork, a glass of water, a spirit lamp

Middle

12 min

17 min

 Learning new topic

Aim:

- to study the principle of operation of the heat engine;

- to study of determining the efficiency of a heat engine;

On today's lesson, we will look at the work of gas and steam during expansion, get acquainted with thermal engines.

·         Slide presentation:  The presentation defines a heat engine as a system that converts thermal energy to mechanical work.  Most engines use a piston moving in a cylinder.  The trapped volume of gas inside the cylinder is the working fluid. 

A heat engine – any device that is capable of converting thermal energy (heating) into mechanical energy (work). We will consider an important class of such devices whose operation is cyclic.

Heating – the transfer of energy to a system by thermal contact with a reservoir.

Work – the transfer of energy to a system by a change in the external parameters (V, el.-mag. and grav. fields, etc.).

The main question we want to address: what are the limitations imposed by thermodynamic on the performance of heat engines?

The principle of operation of heat engines. When heated, the internal energy of a gas or vapor increases, the steam expands and does work (pushes the tube out of the tube).

There are several types of heat engines:

- Steam engine;

 - internal combustion engine;

 - steam and gas turbines;

 - jet engine.

The internal combustion engine was created in 1860 by a French engineer E. Lenoir. Its improvement has quickly gone and now it is the most widespread thermal engine and the engine in general.

Let us consider the simplest single-cylinder engine.

The principle of operation of the internal combustion engine:

Four-stroke internal combustion engines operate on cars and light aircraft. The diagram shows the four cycles of the engine:

Inlet -> Compression -> Working stroke -> Release

Teacher Actions: organize a dialog with students according to new topic, show presentation and provide students with new information.

Student actions: students listen to the teacher, try to answer the questions, write main aspects in copy books.

Feedback: teacher-student, student-student

Task: solving problems

Aim: understand the main aspects and to be able to solve problems about topic.

Teacher’s action: give task to students, ask some questions, check student’s work.

Student’s action: students read the text of every problem carefully, solve the problems and can ask some questions.

Feedback: teacher-student, student-student

Presentation

App 1

End

1 min

(W) Students’ Reflection

1. What is the topic of the lesson?

2. What was your goal in the beginning of the lesson?

Home task:

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

Give problem questions

Student-student assessment

Student-teacher assessment

Rules of Technics of Safety at chemistry room

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 or achievements/difficulties of individuals that will inform my next lesson?