Topicmc1047a7efe5c3e49_1528449000663_0Topic

How to measure force?

Levelmc1047a7efe5c3e49_1528449084556_0Level

Second

Core curriculummc1047a7efe5c3e49_1528449076687_0Core curriculum

III. Planning and conducting experiments and drawing conclusions based on their results.

Timingmc1047a7efe5c3e49_1528449068082_0Timing

45 minutes

General learning objectivesmc1047a7efe5c3e49_1528449523725_0General learning objectives

Using the force meter.

Key competencesmc1047a7efe5c3e49_1528449552113_0Key competences

1. Identifying the device for measuring force.

2. Reading out the magnitude of force using the force meterforce meterforce meter.

Operational (detailed) goalsmc1047a7efe5c3e49_1528450430307_0Operational (detailed) goals

The student:

- describes the construction of the force meter,

- identifies the force magnitude on the force meter.

Methodsmc1047a7efe5c3e49_1528449534267_0Methods

1. Clasroom experiment.

Forms of workmc1047a7efe5c3e49_1528449514617_0Forms of work

1. Group work during experiments.

2. Work with the whole class.

Lesson stages

Introductionmc1047a7efe5c3e49_1528450127855_0Introduction

In the picture a man is pushing a trolley. The force of action is marked in the picture.mc1047a7efe5c3e49_1527752256679_0In the picture a man is pushing a trolley. The force of action is marked in the picture.

[Illustration 1]

Task 1

a) Name three properties of the acting force.

b) What kind of device can you measure force with?

Proceduremc1047a7efe5c3e49_1528446435040_0Procedure

Experiment: Constructing a simple dynamometerdynamometerdynamometer

Research problem:

How to design a simple force meterforce meterforce meter?

Research hypothesis:

Stretching of a springspringspring is related to the linear dependence between magnitude of the force and the deformation of the spring.

[Illustration 2]

The linear dependence of the spring length on the force applied to it can be used to build a device measuring the force value. We only need to scale the force gauge, i.e. a spring with weights.

[Slideshow]

Experiment: Force meter

Aim: Construction of a device for measuring force (force meter)

You will need:

a) a spring,

b) five weights with the massmassmass of 100 g each,

c) a tripodtripodtripod with handles,

d) a piece of graph papergraph papergraph paper glued on a cardboard or a ruler.

Instruction:

1) Attach one end of the springspringspring to the tripod arm.

2) Put the weightweightweight of 100 g on the spring.

3) On the piece of paper or a ruler, mark the position of the weight (it will correspond to 1 N).

4) Add the other weights to the spring and repeat steps 2) to 4) for two (2 N), three (3 N), four (4 N) and five (5 N) weights, respectively.

5) Measure a weightweightweight of a selected body, e.g. a ballpen.

Experiment summary:

This device you have just constructed is the force meterforce meterforce meter and it is used for measuring force. Now you can use it to measure the weight of bodies whose weight does not exceed half a kilogram!

Task 2

Open the applet and follow the instructions.

[Geogebra applet]

Task 3

Describe the elements of construction of the force meter.

Task 4

Identify the magnitudes of forces on the force meter, for the weights of 100 g, 200 g and 250 g.

Task 5

What value of force will the force meter show, if we hang on it 6 weights of 50 g each?mc1047a7efe5c3e49_1527752263647_0What value of force will the force meter show, if we hang on it 6 weights of 50 g each?

Lesson summarymc1047a7efe5c3e49_1528450119332_0Lesson summary

The force meterforce meterforce meter is a device used to measure the magnitude of acting force.

Selected words and expressions used in the lesson plan

dynamometerdynamometerdynamometer

force meterforce meterforce meter

gramgramgram

graph papergraph papergraph paper

massmassmass

measurementmeasurementmeasurement

measuring scalemeasuring scalemeasuring scale

springspringspring

tripodtripodtripod

weightweightweight