Title: How do we measure velocity?

Supplementary material for use in lessons in the group of natural sciences (nature, biology, chemistry, geography, physics), additional classes, science clubs. It can serve as a resource for expanding knowledge, preparing students for science competitions.

Author: Zyta Sendecka

Target Group

Pupils of the seventh grade of primary school (physics).

Core Curriculum

Grade VII – physics

II. Movement and forces. Pupil:

4) uses the concept of velocity to describe straight line motion; calculates its value and converts its units; apply to velocity the relationship of distance and time in which something travels.

The general aim of education

Students explain the concept of velocity and use the relationship of velocity with distance and time for calculations.

Criteria for success

• define velocity;

• calculate the velocity of a moving object;

• use the appropriate measurement units of velocity.

Key competences

• Communication in the mother tongue;

• Communication in foreign languages;

• Mathematical competence and basic competences in science and technology;

• Digital competence;

• Learning to learn;

• Social and civic competences.

Methods/techniques

Work with the text, workshop method, brainstorming.

Individual work and work in pairs.

Teaching aids

• abstract;

• tablets/computers;

• interactive or traditional board;

• a tape measure;

• a stopwatch

Lesson phases

Introduction

1. The teacher gives the subject and the purpose of the lesson in a language that the student understands as well as the criteria for success.

Realization

1. The teacher instructs the students to perform „Experiment 1” in pairs.

2. Students prepare a table to present their results.

3. The teacher asks students to interpret their results. The teacher leads the conversation in such a way as to draw attention to the concept of velocity.

4. The teacher asks students what they think velocity is. Then writes the students answers on the board. The teacher then explains that the term „velocity” cannot be used interchangeably with the word „speed”.

5. The teacher defines velocity and shows the formula to calculate it and it’s units of measurement.

6. The teacher presents the method of calculating the velocity using as examples two selected results from students. The students calculate the velocity they have achieved.

7. Students compare their maximum velocities with the velocities shown in the interactive illustration.

8. Work of the whole class team. Students stand in a circle. The teacher encourages them to play: throws a ball or mascot to one of the students, saying the English word or notion learned in the lesson. The student gives the Polish equivalent, mentions another word in English and throws a ball or mascot to a friend or colleague

Summary

1. Students perform interactive exercises.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

How do we measure speed?

If we know the distance we have travelled and the time in which it took, then we can calculate the velocity of our movement. Just divide the distance travelled by the time taken. The speed tells us, what distance we travel in a given time.

$\mathrm{velocity}=\frac{\mathrm{distance}}{\mathrm{time}}$

A unit of speed is meters per second (m/s). However, in everyday life we give the speed in kilometers per hour (km/h), because it is difficult to precisely measure the distance that we travel in one second. If you compare the speeds of different objects, e.g. two cars, they should be given in the same units. So what should be done if the speed of one of them is given in m/s, and the other in km/h? It’s simple: remember that a kilometer is 1000 m and an hour is 3600 s. So if you're riding a bike at 18 km/h, it means your speed is:

$18\frac{\mathrm{km}}{h}$ = $18·\frac{1000m}{3600s}$ = 18/3,6 = 5 m/s.

If this calculation seems too complicated – you're absolutely right. There is more natural way to do this.

• Movement is the motion of one thing relative to another thing.

• Knowing the distance travelled and the time it took to complete, we can calculate the velocity of an object.