2.1 Physical quantities and units, 2.2 Making measurements and analysing data & 2.3 Nature of quantities

What are the 7 base units?

mass (kg), length (m), time (s) current (A), temperature (K), amount of substance (mol), luminous intensity (cd)

What are derived units?

A unit that is a combinations of base units

What is a homogeneous formula?

The units of the LHS of the formula are the same as the RHS

What is the multiplying factor for T (tera)?

10¹²

What is the multiplying factor for G (giga)?

10⁹

What is the multiplying factor for M (mega)?

10⁶

What is the multiplying factor for K (kilo)?

10³

What is the multiplying factor for m (milli)?

10⁻³

What is the multiplying factor for μ (macro)?

10⁻⁶

What is the multiplying factor for n (nano)?

10⁻⁹

What is the multiplying factor for p (pico)?

10⁻¹²

What is the multiplying factor for f (femto)?

10⁻¹⁵

What is the error of a measurement?

The difference between the measured value and the true value of the quantity

What is the absolute uncertainty of a measurement?

An estimate of the maximum error of a measurement, calculated by halving the range

What is the percentage uncertainty of a measurement?

An estimate of the maximum error of a measurement, given as a percentage of the value

Percentage uncertainty = uncertainty / measurement x 100

How are uncertainties combined when two or more measurements are added or subtracted?

The absolute uncertainties are added together

How are uncertainties combined when two or more measurements are multiplied or divided?

The percentage uncertainties are multiplied together

How are uncertainties combined when a measurement is raised to a power?

The percentage uncertainty is multiplied by the power

What do error bars represent?

The absolute uncertainties in the data

What do the worst acceptable lines on a graph show?

The expected range of possible positions of the line of best fit

How can the uncertainty be interpreted from a graph?

By finding the biggest difference between the gradient of the line of best fit and the worst-fit lines

What is the percentage difference?

How close the experimental value achieved from an experiment is to the accepted value

Percentage difference = (measured value - accepted value) / accepted value x 100

What is a random error?

An error that causes the readings to be spread about the true value, due to results varying in an unpredictable way

How can the effect of random errors be reduced?

By making more measurements and calculating the mean

What is a systematic error?

An error that causes readings to be different from the true value by a predictable amount

What is a zero error?

When an instrument does not read zero when it should

What is a parallax error?

The error that occurs when the line of sight of the person making a measurement is not perpendicular to the scale

What affect do random errors have on a graph?

A scatter of points are about the thine of best fit

What affect do systematic errors have on a graph?

The line of best fit is moved away from where it should be

What is a precise measurement?

A measurement where there is very little spread about the mean value

What is a accurate measurement?

A measurement that is close to the true value

What are repeatable measurements?

Measurements where the same results are obtained if the original experimenter repeats the experiment w/ the same equipment

What are reproducible measurements?

Measurements where similar results are obtained if a different experimenter repeats the experiment w/ different equipment

What is the resolution of a measuring instrument?

The smallest change in the quantity being measured that the instrument can detect

Is displacement a vector or scalar quantity?

Vector

Is velocity a vector or scalar quantity?

Vector

Is acceleration a vector or scalar quantity?

Vector

Is force a vector or scalar quantity?

Vector

Is momentum a vector or scalar quantity?

Vector

Is torque a vector or scalar quantity?

Vector

Is moment due to a force a vector or scalar quantity?

Vector

Is distance a vector or scalar quantity?

Scalar

Is speed a vector or scalar quantity?

Scalar

Is mass a vector or scalar quantity?

Scalar

Is temperature a vector or scalar quantity?

Scalar

Is time a vector or scalar quantity?

Scalar

Is pressure a vector or scalar quantity?

Scalar

Is energy a vector or scalar quantity?

Scalar

Is work done a vector or scalar quantity?

Scalar

Is power a vector or scalar quantity?

Scalar

What is a scale vector diagram?

A diagram with the vectors drawn to the correct length according to the given scale and the angles have been drawn the correct size using a protractor

What is the vertical component of the vector F with the angle θ to the horizontal?

Fsinθ

What is the horizontal component of the vector F with the angle θ to the horizontal?

Fcosθ

Why is momentum a vector?

Momentum is the product of mass and velocity, and velocity is a vector

Why does the mass of a box on a slope not affect the angle at which it begins to slip?

As the mass increases, the weight increases, but so does the frictional force ∴ the mass cancels and does not affect the angle