# Basics

## What to expect

This section is the place to start if you are commencing your course or kicking your revision into gear. Having a good understanding of the basics is essential for the topics.

After studying this topic, you should be able to: ## Key questions

The radian is a unit of angle, similar to degrees. When converting between degrees and radians, we use the fact that a complete circle is 360° = 2π radians. Find out more.

#### Is trigonometry SOH CAH TOA?

Trigonometry is the calculation of angles and lengths of triangles using maths. The sides of a right angled triangle are always in the same ratio for a given angle. These ratios are called sine cosine and tangent (sin, cos and tan). To define which side is which they are given names. Find out more.

#### What are the metric prefixes?

Unit prefixes are used to reduce the characters needed to represent a number. Unit prefixes are written immediately in front of the unit (without a space). Apart from the kilo (k), an uppercase prefix represents a large number and lowercase prefixes represent small numbers. Find out more.

#### How do you calculate percentage uncertainty?

A fractional uncertainty (or percentage uncertainty, if x100%) is the ratio of the absolute uncertainty to the measurement itself. Find out more.

#### What are the differences between scalar and vector quantities?

A scalar quantity is a measurement with magnitude (and usually a unit). A vector quantity is a measurement with magntiude, direction (and usually a unit). Vectors are usually drawn with an arrow in the correct direction, where the length of arrow represents the magnitude. Find out more.

#### How do you calculate density?

Density is defined as the ratio of the mass of a body to its volume. Find out more.

#### What is intensity of light in physics?

The intensity of a wave is the power incident on a surface per unit area. Find out more.

• ### Mathematics

In physics, maths is used as a tool to solve problems related to the relationships between quantities.

• ### Greek alphabet

Almost all of the letters of the Greek alphabet are used to represent physical quantities and units.

• ### Units

In IB Physics there are six fundamental units from which all others required can be derived.

• ### Prefixes

You actually get a list of these in the databook but it's better if you know them.

• ### Presenting data

There are a few rules to follow when presenting data...

• ### Error and uncertainty

An error is the difference between the value you determine and the true value.

• ### Scalars and vectors

All physical quantities can be classified as either a scalar or a vector.

• ### Density

Density is perhaps the most-used concept in physics that doesn't have a specific location in the Subject Guide. It can be used in gases, standing waves, gravitation, fuels and heat transfer.

• ### Intensity

Density is perhaps the most-used concept in physics that doesn't have a specific location in the Subject Guide. It can be used in gases, standing waves, gravitation, fuels and heat transfer.