Topic One (1.1): Length, Time and Units

Course Introduction

Physics is about clearly understanding how the universe works. For this we need strong skills in thinking and communicating, clearly and precisely. These are the hardest to build, but also the most valuable: they grow with practice, but it really helps to keep the principles listed below in your mind as you work. These skills are also really useful for many other areas of life, work and business! Accurately calculating quantities is very important in physics, so you need to be reliable in basic mathematical skills like rounding, standard form and converting units.

Here is an important checklist to help you with your studies of Physics:

  • Read slowly and carefully
  • Learn key terms, definitions, laws and units thoroughly
  • Visualise clearly, with labelled sketches
  • Write full working
  • Rearrange formulas using the triangle method (covered on coursebook p19)
  • Check working carefully
  • Always be aware of units and accuracy
  • Round answers to appropriate significant figures
  • Use standard form
  • Make good use of your calculator – enter calculations as they appear on paper
  • Watch out for converting units, especially with rates, areas or volumes
  • Watch out for other traps, like round-trip distances, number of intervals, etc

A more detailed study guide can be found here STUDY SKILLS FOR PHYSICS.  We advise you to refer to it throughout the course.

The pages in the first part of the book also cover use of common scientific measuring equipment, and the double page spread in the back of the book goes into a bit more detail about errors that can be made when taking these measurements.

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For this Topic, you will need to work through pages 12-17 and pages 282-283 in your coursebook and solve the questions on each double-page spread. You can find the answers at the end of your coursebook on page 320. In order to refresh your maths knowledge and improve your essential mathematical skills please read pages 294-296.

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Please measure the length of your table three times and compare the results. Is there any error? Why?

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Please study the resources below to help with your understanding of measurements:

As some of your calculations will involve both very large and very small numbers, here is a video reminding you about powers of ten.

WATCH - Powers of Ten (YouTube) Links to an external site.

The International System of Units (SI) is more commonly known as the metric system and is the agreed international system of measurement.  Here are a few resources which explain more about SI units.

READ – SI Units and Prefixes

WATCH – SI Units and Derived Units (YouTube) Links to an external site.

WATCH - Cowen Physics: SI Base Units and Derived Units (YouTube) Links to an external site.

In Physics, we sometimes need to convert units in our calculations.  Here are two documents which should be downloaded and used for reference in module one and in your later work.

READ – Converting Units Download READ – Converting Units

READ – Converting Rates Download READ – Converting Rates

The Kilogram (Kg) is the SI unit of mass.  Here are two interesting videos about the development of this unit.

WATCH - The Kg is Dead, Long Live the Kg, from Veritasium (YouTube) Links to an external site.

Accuracy and precision are often misunderstood.  Here are two resources to help clarify their meaning.

WATCH - Accuracy vs Precision (YouTube) Links to an external site.

READ – Measurement Accuracy and Uncertainty Download READ – Measurement Accuracy and Uncertainty

Please use the following resource if you need extra help using your calculator in Physics calculations.

READ - A Note About Calculators Download READ - A Note About Calculators

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If you would like to study this topic in more depth or are aiming for grades A/A*or 7-9, please complete our extension worksheet. 

COMPLETE - Extension Worksheet 1.1 Download COMPLETE - Extension Worksheet 1.1

CHECK - Extension Worksheet 1.1 Answers Download CHECK - Extension Worksheet 1.1 Answers