Topicm11cc1b93809015ed_1528449000663_0Topic

Solving problem tasks related to with workworkwork, powerpowerpower and energyenergyenergy

Levelm11cc1b93809015ed_1528449084556_0Level

Second

Core curriculumm11cc1b93809015ed_1528449076687_0Core curriculum

III. Energy. The student:

1) uses the concept of kinetic, potential gravity and potential elasticity energy; describing the workworkwork done as the change of energyenergyenergy;

2) determines the change of potential energypotential energypotential energy of gravity and kinetic energykinetic energykinetic energy;

3) uses the principle of energy conservatioprinciple of energy conservationprinciple of energy conservatio n to describe phenomena and the principle of mechanical energy conservation for calculations.

Timingm11cc1b93809015ed_1528449068082_0Timing

45 minutes

General learning objectivesm11cc1b93809015ed_1528449523725_0General learning objectives

Revising the knowledge related to work, power and energy.

Key competencesm11cc1b93809015ed_1528449552113_0Key competences

1. Using the concept of work, power and energy.

2. Describing energy transformation.

3. Using the principle of mechanical energy conservation.

Operational (detailed) goalsm11cc1b93809015ed_1528450430307_0Operational (detailed) goals

The student:

- using the concept of workworkwork, power and energyenergyenergy,

- using the principle of mechanical energy conservation to do tasks.

Methodsm11cc1b93809015ed_1528449534267_0Methods

1. Flipped classroom.

2. Grading difficulties.

Forms of workm11cc1b93809015ed_1528449514617_0Forms of work

1. Individual student work while solving tasks.

2. Discussion.

Lesson stages

Introductionm11cc1b93809015ed_1528450127855_0Introduction

Introductory tasks.

Do the following tasks.

1. Zdzisław moved a package lying on the floor over the distance of 3 m. Then he did the work of 0,6 kJ. Calculate the value of the force that he worked with (assume that it had the horizontal direction and a constant value).

2. The SIndeks dolny 1₁ engine did the work of 120 J in 20 s, and the SIndeks dolny 2₂ engine did the work of 1,8 kJ in 5 minutes. Which one has more powerpowerpower?

3. Calculate the power of the radio which consumes 0,6 kWh of energyenergyenergy in 3 hours (1 kWh = 1000 W · 3600 s = 3600000 J).

Answer:

1. 200 N.
2. Their powers are the same.
3. 200 W.

Procedurem11cc1b93809015ed_1528446435040_0Procedure

[Interactive illustration]

Please take the repetition test.

Task 1

Which formula is used to determine workworkwork?

a) $F=\frac{m}{g}$ 
b) $E=sh$ 
c) $W=Fs$ 
d) $P=Wt$

Task 2

Which formula is used to define powerpowerpower?

a) $W=Fs$ 
b) $P=\frac{W}{t}$ 
c) $E=mgh$ 
d) $P=\frac{t}{W}$

Task 3

The unit of work is:

a) volt
b) joule
c) niuton
d) wat

Task 4

The unit of power is:

a) joule
b) niuton
c) wat
d) ampere

Task 5

When is the body able to do workworkwork?

a) When it has speed.
b) When it is accelered.
c) When we blow on it with a hairdryer.
d) When it has energy.

Task 6

What quantities characterise potential energypotential energypotential energy?

a) Speed, time and distance.
b) Mass and height.
c) Feight, mass and gravitational acceleration.
d) ForceforceForce, distance and friction.

Task 7

What quantities characterise kinetic energyenergyenergy?

a) Acceleration and mass.
b) Speed and height.
c) Mass and speed.
d) Force and height.

Task 8

If the speed of the body increases 2 times, its kinetic energykinetic energykinetic energy:

a) Will increase 5 times.
b) Will remain the same.
c) Will decrease 4 times.
d) Will increase 4 times.

Task 9

If a jar with 1 kg of preserve is moved to the height of 1 m, its potential energy equals:

a) 1 J.
b) 10 J.
c) 100 J.
d) 1000 J.

Task 10

When do we not do work in the physical sense?

a) When we move the body at a distance acting with a force.
b) When we lift the body to a certain height.
c) When we bring the shopping.
d) When we dig a hole and throw the soil out of it.

Answers to the test.

1 - c, 2 - b, 3 – b, 4 - c, 5 - d, 6 - c, 7 – c, 8 – d, 9 – b, 10 – c.

Please do the following tasks.

Task

Calculate the kinetic energykinetic energykinetic energy of a body weighing 2 kg, which moves at the speed of 5 $\frac{m}{s}$.

Answer: 25 J.

Task

What is the mass of the body which was moved to the height of 5 m and has the potential energypotential energypotential energy of 100 J?

Answer: 2 kg.

Task

What work will Staś do while moving the table using the forceforceforce of 60 N over the distance of 5 m?

Answer: 300 J.

Task

What was the power of the worker who did workworkwork of 3600 J in 10 minutes?

Answer: 6 W.

Task

What work will the 1,2 kW engine do if it works for 120 seconds?

Answer: 144 kJ.

Lesson summarym11cc1b93809015ed_1528450119332_0Lesson summary

Solving the proposed tasks will result in a thorough revision of the knowledge related to work, power and energy.

Selected words and expressions used in the lesson plan

displacementdisplacementdisplacement

energyenergyenergy

forceforceforce

kinetic energykinetic energykinetic energy

potential energypotential energypotential energy

powerpowerpower

principle of energy conservationprinciple of energy conservationprinciple of energy conservation

simple machinessimple machinessimple machines

windlasswindlasswindlass

workworkwork