Energy. Kinetic and potential energy.

Subject

Physics

Lesson Topic

Energy. Kinetic and potential energy.

Class

7

date

«____»________________2019 year

Duration

40 min

location

School Yntymak

quantity

Present:

Absent:

The purpose of the lesson:

To define the energy, kinetic and potential energy; To enter formulas for the calculation of kinetic and potential energy;

Language objectives:

Students know and apply the terms:

Kinetic energy

Potential energy

Work

Weight

Acceleration free fall

Height

Expected results on the subject:

Students are able:

1.Use the meaning of kinetic and potential mechanical energy.

2. Learn to solve problems using the formulas of potential and kinetic energy.

3. Learn to recognize the types of mechanical energy.

4. Learn about the use of mechanical energy.

Expected results by language:

Students know and use the following terms:

Kinetic energy, Potential energy,Work, Weight, Acceleration free fall, Height

Students know and use the following phrases:

1.Energy is a physical quantity that characterizes the ability of a body or system of bodies to do work.

2.Two types of mechanical energy are distinguished: potential and kinetic.

3. An object has potential energy by virtue of its position.

Kinetic energy is possessed by a moving object by virtue of its motion.

Necessary equipment and devices:

1.Computer complete with multimedia projector

2. Presentation on the topic

3. Handout material

Additional resources:

1. Textbook

2. Markers

3. Posters

4. Stickers

Stage lesson

Tasks and Exercises

Time

1.Organizing time

Greeting students, conducting an inventory, checking the cleanliness of the classroom, checking students' readiness for the lesson

2 minutes

2.Repetition of the previous material

1. What physical quantity do we call mechanical work?

(Mechanical work is a physical quantity equal to the product of force on the traversed path)

2.How to calculate the mechanical work?

(A = F • s, (J) - write on the board)

3. What are the conditions for doing mechanical work?

Consequences of the formula:

1. if F ↑↑ ν, then A> 0

2. If F ↑ ↓ ν, then A <0

3. If F┴ ν, then A = 0

4 minutes

3. Statement of the learning situation

Demonstration of experience with the mill.

Questions:

1.What forces act on the cargo? (Gravity and strength of elasticity)

2.What force does the work? (The force of gravity and the force of elasticity do the work, the force of gravity does positive work, the force of elasticity-negative work)

Demonstration of experience with the machine:

1. What forces act on the machine? (Gravity, reaction force of the support, frictional force)

2.What force does the work? (The friction force does negative work)

Demonstration of experience with a spring:

1.What forces act on the spring? (Gravity and strength of elasticity)

2.What force does the work? (Force of elasticity)

The elastic force performs work on stretching the spring, hence the spring itself performs work.

It is said that the body or system of interacting bodies, capable of doing work, has energy.

5 minutes

4. Studying new material

Energy is a physical quantity that characterizes the ability of a body or system of bodies to do work. Mechanical energy is measured by the amount of work that a body or a system of bodies can perform.

The system consisting of the globe and located at a certain height above the body, has energy, since this body can fall in the work when it falls.

The deformed spring and the body lifted above the Earth have energy regardless of whether they are currently doing work or not: the energy characterizes the state of the system, the ability of the system to perform work when transferring from this state. From these examples it is evident that the energy is connected either with the motion of bodies, or with the mutual arrangement of bodies or parts of the system. There fore, two types of mechanical energy are distinguished: potential and kinetic.

Mechanical energy

potential energy kinetic energy

/ Interaction energy / / Energy of motion /

Е_Р=А_max=mgh ,( J) Е_k= , (J)

Kinetic energy - Кинетическая энергия

Potential energy - Потенциальная энергия

Work- Работа

Weight- вес

Acceleration free fall- Ослабление свободного падения

Height- Высота

18 minutes

5.Solidification of the studied material in the process of solving problems

1. A ball weighs 0.5 kg on a horizontal table with a constant speed

2 m / s. What is its kinetic energy?

Given: Solution:

M = 0.5 kg Ek = (mν ^ 2) / 2

Ν = 2 m / sEk = (0.5 kg • 〖(2 m / s)〗 ^ 2) / 2 = 1 J

To find:

Ek-? Answer: 1 J

What is the potential energy of this ball? (The potential energy is zero, because the potential energy is the energy that is determined by the mutual position of the interacting bodies or parts of the same body)

2. A ball weighing 200 g, moving at a speed of 2 m / s, rose vertically upward to a height of 1 m. What is the energy of the ball?

Given: Solution:

M = 200 g = 0.2 kg E = EP + Ek

Ν = 2 m / sE = mgh + (mν ^ 2) / 2

H = 1 mE = 0.2 kg • 10 N / kg • 1 m + (0.2 kg • 〖(2 m / s)〗 ^ 2) / 2 = 2 + 10 = 12 J

To find:

E-? Answer: 12 J

3. What do we get acquainted with the physical quantity - mechanical energy?

(For solving problems, to be able to explain the physical picture of the world in which we live)

A world that has an amazing property - a property of conservation.

10 minutes

6.Total Lessons

Work in pairs to complete the table (self-filling, self-test)

On two languages

In Russian

In English

3 minutes

7. Reflexion

I would like to know what was the moment of the lesson you liked?

2 minutes

8.Home job

1. Try to explain the physical meaning of the saying

"What are you spending, climbing uphill, you will return on the descent?"

2.Sovlet and solve: 1 option - the problem of kinetic energy, 2 option - the problem of potential energy.

3.§ ----------------

1 minutes