SI units

The prefixes nano (n), micro ($\mu$) and pico (p) are often paired with units. Which row gives their correct values?

Feb/March 2016

In SI, the unit of specific heat capacity is $\text{J kg}^{-1}\,\text{K}^{-1}$. State the unit of specific heat capacity in SI base units?

Feb/March 2016

Which expression has SI base units that are the same as those of pressure?

Feb/March 2017

Which unit has the same value as the coulomb?

Feb/March 2018

Which row gives a quantity and an incorrect unit?

Feb/March 2018

When the temperature is near $0\,\text{K}$, the specific heat capacity of a certain solid is described by $c = bT^3$, where $T$ denotes temperature and $b$ is a constant specific to the solid. The SI unit of specific heat capacity is $\text{J kg}^{-1}\text{K}^{-1}$. In SI base units, what is the unit of the constant $b$?

Feb/March 2019

The ampere, metre and second are SI base units. State two more SI base units.

Feb/March 2019

A byte (b) is made up of 8 bits. How many bits does 1 terabyte (1 Tb) contain?

Feb/March 2020

What physical quantity could be expressed in units of $\text{N s}^2\,\text{m}^{-1}$?

Feb/March 2021

A computer memory stick has a label showing a storage capacity of $128\ \text{GB}$. The letter B represents byte, which is a unit. What is the equivalent storage capacity?

Feb/March 2022

Which row gives a physical quantity together with its base unit in the SI system?

Feb/March 2024

Table 1.1 shows several SI quantities. Complete the table by placing a tick () in the rows that are SI base quantities.

Feb/March 2024

Pressure multiplied by volume has the same SI base units as

May/June 2010

the quantity whose SI base units are the same as those of pressure × volume

May/June 2010

Prefixes are often used when writing a unit. For instance, the gram can take the prefix ‘kilo’ to give kilogram. A prefix shows a power-of-ten. Here, that power-of-ten is $10^3$. Complete Fig. 1.1 by matching each prefix to its symbol and power-of-ten.

May/June 2010

Decimal sub-multiples and multiples of units are shown by attaching a prefix to the unit. For instance, the prefix milli (m) means $10^{-3}$. Which row shows the sub-multiples or multiples represented by pico (p) and giga (G)?

May/June 2011

To verify the calculations, the units are substituted into the equations below alongside the numbers. Which equation has to be incorrect?

May/June 2011

Prefixes are added to units to show decimal sub-multiples and multiples. For example, milli (m) stands for $10^{-3}$. Which row shows the sub-multiples or multiples represented by pico (p) and giga (G)?

May/June 2011

How is the unit watt expressed using SI base units?

May/June 2012

State the SI base unit for volume.

May/June 2012

A material has a property $Q$ that is used to describe how sound waves behave in the material. $Q$ is given by the pressure $P$ of the sound wave divided by the wave speed $v$ and the surface area $A$ of the material through which the wave passes: $Q = \frac{P}{vA}.$ What are the SI base units of $Q$?

May/June 2013

In SI base units, what is the unit for power?

May/June 2013

Work out the SI base units of power.

May/June 2013

State the SI base units for force.

May/June 2013

Which pair of units includes one derived unit and one SI base unit?

May/June 2014

What value is equal to 2000 microvolts?

May/June 2014

The unit of specific heat capacity is $\text{J kg}^{-1}\text{K}^{-1}$. How is this expressed using SI base units?

May/June 2014

Show that the SI base units for power are $\text{kg m}^2 \text{s}^{-3}$.

May/June 2014

In the list below, underline all the base quantities: ampere, charge, current, mass, second, temperature, weight.

May/June 2014

Which one is an SI base unit?

May/June 2015

For a vehicle travelling at speed $v$, if a constant braking force is exerted, the distance $d$ travelled as it comes to rest is described by $d = kv^2$, where $k$ is a constant. If $d$ is given in metres and $v$ is given in metres per second, the constant takes the value $k_1$. When the distance is measured in metres and the speed is measured in kilometres per hour, what is the value of the constant?

May/June 2015

For a gas molecule, the mean kinetic energy $E$ is represented by $E = \frac{3}{2} k T$, with $T$ denoting the absolute (kelvin) temperature. What are the SI base units of $k$?

May/June 2015

Which unit does not appear in either the definition of the coulomb or the definition of the volt?

May/June 2015

Which statement contains the correct unit?

May/June 2015

What does the joule (J) equal in SI base units?

May/June 2015

Which energy value is not $2400\,\text{J}$?

May/June 2016

Which pair of quantities has different SI base units?

May/June 2016

Which quantity, together with its unit, is correct?

May/June 2016

The luminosity $L$ of a star is defined by $L = 4\pi r^2 \sigma T^4$, where $r$ represents the star's radius, $T$ denotes the star's temperature, and $\sigma$ is a constant with units $\text{W m}^{-2}\,\text{K}^{-4}$. What are the SI base units of $L$?

May/June 2016

Which list includes only SI base units?

May/June 2016

State the SI base units for the quantity $\dfrac{\text{pressure}}{\text{density}}$?

May/June 2017

Which expression, written in SI base units, is equivalent to the volt?

May/June 2017

Which unit may be written in base units as $\text{kg m}^2\text{ s}^{-2}$?

May/June 2019

The luminosity $L$ of a star is represented by $L = 4\pi r^2 \sigma T^4$ in which $r$ denotes the star’s radius, $T$ denotes the star’s temperature and $\sigma$ is a constant with units $\text{W m}^{-2}\text{ K}^{-4}$. What are the SI base units of $L$?

May/June 2019

What has the same value as 2000 microvolts?

May/June 2019

How many SI base units are needed to express electric field strength and power?

May/June 2019

Which unit is an SI base unit?

May/June 2019

Which two units are combined to define the volt?

May/June 2019

Use an expression for work done in terms of force to show that the SI base units of energy are $\text{kg m}^2\text{s}^{-2}$.

May/June 2020

Which quantity might be expressed in units of $\text{N m V}^{-1}$?

May/June 2021

Which two units are the same when written in terms of SI base units?

May/June 2022

What symbol represents the SI base unit of temperature?

May/June 2022

Which list of unit prefixes reduces in magnitude from left to right?

May/June 2022

The drag coefficient $C_d$ is a dimensionless quantity. It is used to compare the drag on different cars at different speeds. $C_d$ is given by the equation $C_d = \frac{2F}{v^n \rho A}$, where $F$ is the drag force on the car, $\rho$ is the density of the air, $A$ is the cross-sectional area of the car and $v$ is the speed of the car. Find the value of $n$.

May/June 2022

Which unit is not one of the SI base units?

May/June 2023

Gm, Tm, $\mu$m and pm are each units used for length. Which of these units is the largest, and which is the smallest?

May/June 2023

How is the ohm written in SI base units?

May/June 2023

What is the meaning of pressure?

May/June 2023

Which unit counts as an SI base unit?

May/June 2024

Which one of the following may have the same units as force?

May/June 2024

Which quantity is equal to $0.00005\ \text{J}$?

May/June 2024

A piece of material has cross-sectional area $A$ and length $L$. The temperatures on the two faces of the sample are $T_1$ and $T_2$. Thermal energy $Q$ passes through the sample in time $t$. These quantities obey $\frac{Q}{t} = k \times A \times \frac{(T_1 - T_2)}{L}$, where $k$ is a constant. Determine the SI base units of $k$.

May/June 2025

Which of these units is not the same as a unit of energy?

May/June 2025

A metal sphere with radius $r$ is released into a tank of water. While it descends with speed $v$, it is acted on by a drag force $F$ defined by $F = krv$, where $k$ is a constant. What are the SI base units of $k$?

Oct/Nov 2010

Which row gives a base quantity together with its correct SI unit?

Oct/Nov 2010

Which units are used for work, energy and power?

Oct/Nov 2010

For a sphere moving through a fluid, the frictional force $F$ is defined by $F = 6\pi a \eta v$, where $a$ represents the sphere’s radius, $\eta$ is a constant connected with the fluid, and $v$ is the sphere’s speed. What units does $\eta$ have?

Oct/Nov 2010

A metal sphere with radius $r$ is released into a tank of water. As it moves downward with speed $v$, it experiences a drag force $F$ given by $F = krv$, where $k$ is a constant. What are the SI base units of $k$?

Oct/Nov 2010

Mass and time are two of the SI base quantities. State three of the others.

Oct/Nov 2010

Which statement that uses prefixes of the base unit metre (m) is incorrect?

Oct/Nov 2011

A cylindrical tube rolling down a slope with inclination $\theta$ travels a distance $L$ in time $T$. The relationship between these quantities is $L \left( 3 + \frac{a^2}{P} \right) = Q T^2 \sin \theta$ where $a$ represents the internal radius of the tube and $P$ and $Q$ are constants. Which row gives the correct units for $P$ and $Q$?

Oct/Nov 2011

What is the expression for power in SI base units?

Oct/Nov 2011

Find the ratio $\frac{10^{-3}\ \text{THz}}{10^{3}\ \text{kHz}}$?

Oct/Nov 2011

Which statement that uses prefixes of the base unit metre (m) is incorrect?

Oct/Nov 2011

A cylindrical tube that rolls down a slope with inclination $\theta$ travels a distance $L$ in a time $T$. These quantities are connected by $L\left(3 + \frac{a^{2}}{P}\right) = QT^{2}\sin \theta$. In this expression, $a$ is the tube’s internal radius, and $P$ and $Q$ are constants. Which line gives the correct units for $P$ and $Q$?

Oct/Nov 2011

Which SI base unit(s) are used to express weight?

Oct/Nov 2012

The units for all physical quantities can be written in terms of SI base units. Which pair contains quantities with identical base units?

Oct/Nov 2012

Three of these quantities share the same unit. Which quantity is measured in a different unit?

Oct/Nov 2012

Which row gives an SI base quantity together with the correct unit?

Oct/Nov 2013

Which row gives an SI base quantity together with its correct unit?

Oct/Nov 2013

Which unit corresponds to the coulomb?

Oct/Nov 2013

The spring constant $k$ of a coiled wire spring is described by the formula $k = \dfrac{G r^4}{4 n R^3}$, where $r$ represents the radius of the wire, $n$ is the number of wire turns and $R$ is the radius of each turn of the wire. The quantity $G$ depends on the material that the wire is made from. What is a suitable unit for $G$?

Oct/Nov 2013

State two SI base units apart from kilogram, metre and second.

Oct/Nov 2013

State two SI base units excluding the kilogram, metre and second.

Oct/Nov 2013

For a vehicle travelling at speed $v$, the stopping distance $d$ after the brakes are applied is given by $d = kv^2$, where $k$ is a constant. State the unit of $k$ written in SI base units.

Oct/Nov 2014

Mass, length and time are SI base quantities. State any two further base quantities.

Oct/Nov 2014

Which SI base unit(s) are used to express weight?

Oct/Nov 2015

When the temperature is very near $0\,\text{K}$, the specific heat capacity of a certain solid obeys $c = bT^{3}$, with $T$ representing the thermodynamic temperature and $b$ being a constant for that solid. The SI unit for specific heat capacity is $\text{J kg}^{-1}\text{K}^{-1}$. What is the unit of constant $b$, written in SI base units?

Oct/Nov 2015

A satellite's orbital period $T$ for a circular orbit around the Earth is related by $T^2 = \frac{k r^3}{M}$, where $r$ is the radius of the orbit, $M$ is the mass of the Earth and $k$ is a constant. What are the SI base units of $k$?

Oct/Nov 2015

The Reynolds number $R$ is a constant employed in the analysis of liquids moving through pipes. $R$ is a dimensionless quantity, so it has no unit. $R = \frac{\rho v D}{\mu}$ where $\rho$ represents the density of the liquid, $v$ is the liquid's speed and $D$ is the diameter of the pipe in which the liquid flows. What are the SI base units of $\mu$?

Oct/Nov 2015

The speed $v$ of sound in a gas is described by $v = \sqrt{\frac{\gamma P}{\rho}}$, where $P$ represents the gas pressure, $\rho$ represents its density, and $\gamma$ is a constant. What are the SI base units of $\gamma$?

Oct/Nov 2016

For two point charges $q_1$ and $q_2$ separated by a distance $r$, the force $F$ is described by the equation $F = \frac{k q_1 q_2}{r^2}$, where $k$ is a constant. What are the SI base units of $k$?

Oct/Nov 2016

Define what pressure is.

Oct/Nov 2016

Which SI unit, when expressed in base units, is incorrect?

Oct/Nov 2017

Which pair of units are not equivalent when written in SI base units?

Oct/Nov 2017

The units of specific heat capacity are $\text{J kg}^{-1}\,\text{K}^{-1}$. Which SI base units correspond to specific heat capacity?

Oct/Nov 2017

How many cubic nanometres, $\text{nm}^3$, are contained in one cubic micrometre, $\mu\text{m}^3$?

Oct/Nov 2017

The greatest theoretical power $P$ for a wind turbine is described by the equation $P = k\rho A v^n$, in which $\rho$ represents the density of air, $A$ is the area swept out by the turbine blades, $v$ is the speed of the air and $k$ is a constant with no units. What is the value of $n$?

Oct/Nov 2017

Define the term power.

Oct/Nov 2017

When a beam of light strikes a surface, it transfers energy to that surface. The intensity of the beam is the energy transferred per unit area per unit time. What is the unit of intensity, written in SI base units?

Oct/Nov 2018