Chapter 1

What are the physical quantities?

• • - has direction

• • - something can be measured

  • - has a numerical value and a unit

• • - equation where each term has the same base units

Unit derivation consists of...

• some combination of the base units that may be multiplied together or divided by one another but never added or subtracted

• some combination of the base units that may be added together or subtracted by one another but never multiplied or divided

What is homogeneous equation?

• Equation where each term has the same base units or balanced

• Left hand side equation = Right hand side equation

• Has magnitude and direction

Uncertainty can be classes into...

• systematic and random

• scalar and vector

• systematic and zero

Examples of systematic error?

• reaction time

• zero error

• wrongly calibrated scale

• random error

Example of random errors?

• The scale reading is not zero before measurements are taken

• Reading a scale from different angles, so introducing a variable parallax error

• When timings are carried out manually, it must be accepted that there will be a delay between the experimenter observing the event and starting the timing device

Accuracy refers to the closeness of a measured value to the ‘true value’ or ‘known value’.

In which.....

• Depends on the equipment used, the skill of the experimenter and the techniques used.

• The experimenter may choose different measuring instruments and may use them with different levels of skill, thus affecting the precision of measurement.

What is meant by a scalar quantity?

• A quantity that has magnitude and direction

• A quantity that has only direction

• A quantity that has only magnitude

How to find the value of an uncertainty?

• The smallest division on the instrument

• Half the range of a number of readings of the measurement

How to calculate the percentage uncertainty?

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