Is there a national exam in Grade 11?

No. Ethiopia sets national exams in Grade 6, Grade 8 and Grade 12 only. These cards are for your school's own exams, and for the national exam that comes a few years later.

Where do these cards come from?

They are written against the Ministry of Education textbook for Grade 11 Physics, and every formula, constant and table row is checked again before a card goes up.

Yes. Every card here is free to read and the printable sheet is free to download. Neither needs an account.

When was this last checked?

6 September 2026. Cards arrive chapter by chapter, and the line under each one says when that card was last read through.

Free short notes and revision cards

Grade 11 Physics

Grade 11 Physics on Temari has 11 revision cards, arranged by the chapters of the Ethiopian national curriculum. Every card says when the rule applies, what each symbol in it stands for, and the mistake students most often make with it. They are free to read and need no account.

11
Cards: 10
Reference tables: Free
Price: 6 September 2026
Last checked

Across the whole subject

Telling heat and temperature apartReference tableWhat it is · Where it lives · SI unit · +5

What is compared	Heat	Temperature
What it is	Energy that moves from a hotter body to a colder one.	The degree of hotness or coldness of a body.
Where it lives	Nowhere. A body stores internal energy, and heat is the name for that energy only while it crosses a boundary.	In the body itself, as a property you can read at any moment.
SI unit	Joule (J). Also the calorie, where 1 cal is about 4.186 J.	Kelvin (K). Also degrees Celsius and degrees Fahrenheit.
Does the amount matter	Yes. Heating more mass takes more heat, so a pot of boiling water needed far more than a cup.	No. The cup and the pot both sit at 100 °C.
What it depends on	The mass, the specific heat capacity of the substance, and the temperature change.	The average translational kinetic energy of one particle, not the total for the whole sample.
How you measure it	Indirectly, with a calorimeter, from measured temperature changes and known specific heat capacities.	Directly, with a thermometer.
What zero means	No net heat crosses between two bodies that are already at the same temperature.	0 K is absolute zero and has never been reached, and kelvin values are never negative. 0 °C is an ordinary temperature, the freezing point of water.
The formula	$Q = mc\,\Delta T$ while the temperature changes, $Q = mL$ while the substance changes state.	Read off the scale. A change of 1 °C is the same size as a change of 1 K.

When you use it

Reach for this when a question treats heat and temperature as one word: how much energy warms a mass of water, why the reading stops climbing while ice melts, or why two bodies stop exchanging energy once they are equally hot.

Watch out

Two mistakes cost marks here. The first is using $Q = mc\,\Delta T$ while ice is melting or water is boiling. The temperature stays put during a change of state, so $\Delta T$ is zero and the formula returns zero heat. The right one is $Q = mL$ , and warming ice at -10 °C into steam is several separate steps rather than one. The second is turning a temperature CHANGE into kelvin by adding 273. Water warmed from 20 °C to 70 °C has changed by 50, in °C and in K alike. Add 273 to a temperature, never to a difference.

Conduction and convection comparedReference tableWhat it is · Where it works · How the energy travels · +5

What is compared	Conduction	Convection
What it is	Heat moving through a material while the material itself stays where it is.	Heat carried by the bulk movement of a fluid.
Where it works	In solids, liquids and gases.	In liquids and gases only, because only a fluid can flow.
How the energy travels	From particle to particle by vibration and collision. In a metal, free electrons carry most of it, which is why metals beat wood and water.	The hot fluid itself moves and takes the energy with it, so warm fluid rises and cool fluid sinks. Natural convection is driven by the density difference heating creates, forced convection by a fan or a pump.
Rate law	Fourier's law: $\dfrac{Q}{t} = kA\dfrac{\Delta T}{L}$ , where L is the thickness measured along the direction of flow.	Newton's law of cooling: $\dfrac{Q}{t} = hA(T_s - T_f)$ , where $T_s$ is the surface temperature and $T_f$ that of the bulk fluid.
Unit of the coefficient	k is in $\text{W m}^{-1}\text{K}^{-1}$ , because the conduction law divides by the thickness L.	h is in $\text{W m}^{-2}\text{K}^{-1}$ . There is no L anywhere in the convection law.
Which is faster	Inside one fluid it is the slower of the two. Along a copper bar it beats convection in still air easily, so this is not a universal rule.	Inside one liquid or gas it normally moves heat faster, because the material carries the energy with it.
Across a vacuum	It cannot cross one. Conduction needs matter.	It cannot cross one either. Only radiation crosses empty space.
Everyday examples	A metal spoon warming in hot tea, the base of a cooking pan, the fins of a heat sink.	Water circulating in a boiling pot, land and sea breezes, warm air rising in a room.

When you use it

Use when a question asks how heat gets from one place to another and you have to name the mode, or when you have to put a number on it with Fourier's law or Newton's law of cooling. The medium decides: a solid can only conduct, while a liquid or a gas does both.

Watch out

Two mistakes cost a mark. The first is copying k's unit onto h and writing the convective coefficient as $\text{W m}^{-1}\text{K}^{-1}$ . Divide the law out instead of memorising it: $h = \dfrac{Q/t}{A\,\Delta T}$ , which is $\text{W m}^{-2}\text{K}^{-1}$ . k keeps the extra metre only because the conduction law divides by the thickness L, and there is no L in the convection law at all. The second is answering that conduction works in a vacuum because two solids can touch. It does not. Both modes need matter, and radiation is the only one that crosses empty space, which is why a vacuum flask still loses heat and why the Sun reaches us at all.

Inertia and momentum comparedReference tableWhat it is · Whose it is · When it is there · +6

What is compared	Inertia	Momentum
What it is	The property by which a body resists any change in its state of rest, or of uniform motion in a straight line.	The quantity of motion a body has because of its mass and its velocity.
Whose it is	A property of the body itself, and mass is the measure of it.	A quantity the body has only while it is moving.
When it is there	Always, at rest and in motion alike.	Zero for a body at rest in the frame you are working in, and there as soon as the body moves in that frame.
How it is measured	By mass, so inertia is proportional to m. Mass is a scalar, in kilograms.	$p = mv$ , in $\text{kg m s}^{-1}$ . That is the same unit as the newton second, since $1\,\text{N} = 1\,\text{kg m s}^{-2}$ .
Dimension	Mass, the measure of inertia, carries $[M]$ .	$[M L T^{-1}]$ , mass times velocity.
Direction	It has none. Mass is a scalar.	It is a vector, pointing along the velocity.
What it depends on	In straight line motion, on the mass alone.	On the mass and the velocity together, so a light bullet can carry as much as a heavy body moving slowly.
How it changes	Only if the mass changes, as it does for a rocket burning fuel.	Whenever a net external force acts, and the change equals the impulse of that force.
Everyday examples	A standing passenger falls backwards when the bus starts and forwards when it brakes. Dust leaves a beaten carpet because the dust stays behind.	A moving car, a kicked football and a fired bullet all carry it.

When you use it

Use when a question puts the two words in one sentence: why a parked lorry is hard to push, why a passenger lurches when a bus starts, or what a moving body hands over in a collision. The inertia compared here is the straight line kind, measured by mass, which is a different quantity from the moment of inertia a turning body has.

Watch out

Students hear that a heavy lorry has huge inertia and write that a parked lorry has huge momentum. A body sitting still has all of its inertia and exactly zero momentum, because $p = mv$ and v is zero. The same confusion turns the bus the wrong way round: when the bus starts your body stays at rest and you fall backwards, and you are thrown forwards only when it brakes. Check the velocity before you claim momentum, and ask which way the vehicle is changing speed before you say which way the passenger falls.

Choosing the right equation of motionReference tablev = u + at · s = ut + 1/2at^2 · v^2 = u^2 + 2as · +1

Equation	The quantity it leaves out	Reach for it when
$v = u + at$	$s$	no distance is given or wanted
$s = ut + \tfrac{1}{2}at^{2}$	$v$	the final velocity is unknown
$v^{2} = u^{2} + 2as$	$t$	no time is given or wanted
$s = \left(\dfrac{u+v}{2}\right)t$	$a$	the acceleration is unknown

When you use it

Use for any body moving in a straight line with constant acceleration. List what the question gives you, spot the quantity it never mentions, and take the equation that leaves that quantity out.

Watch out

All four hold only while the acceleration stays constant. A body on a curve, or one whose acceleration changes, needs calculus instead. Take displacement, velocity and acceleration as positive in one direction and negative in the other, or a body thrown upwards gives an answer with the wrong sign.

Newton's laws and momentumReference tableNet force on a mass · Force from momentum · Action and reaction · +3

What you are finding	Formula	Conditions it holds under
Net force on a mass	$F_{net} = ma$	mass constant, $F$ the resultant
Force from momentum	$F_{net} = \dfrac{\Delta p}{\Delta t}$	holds even when mass changes
Action and reaction	$F_{12} = -F_{21}$	always, on two different bodies
Linear momentum	$p = mv$	a vector, along the velocity
Impulse	$J = F\,\Delta t = \Delta p$	constant force over $\Delta t$
Weight	$W = mg$	$g$ is local, not a constant of nature

When you use it

Use when a question asks what a force does to a body: how fast it speeds up, how hard two bodies push on each other, or what a collision leaves behind. Momentum is conserved in every collision; kinetic energy is conserved only in an elastic one.

Watch out

The two forces of the third law act on two different bodies, so they never cancel each other out. Students subtract them from one another and get zero acceleration for a book resting on a table, when the pair that actually balances is the table's push and the Earth's pull, both acting on the book.

Work, energy and powerReference tableWork by a constant force · Kinetic energy · Gravitational potential energy · +4

What you are finding	Formula	Conditions it holds under
Work by a constant force	$W = Fs\cos\theta$	$\theta$ between force and displacement
Kinetic energy	$KE = \tfrac{1}{2}mv^{2}$	speeds well below light speed
Gravitational potential energy	$PE = mgh$	near the ground, $g$ uniform
Work and energy theorem	$W_{net} = \Delta KE$	always, for any net force
Average power	$P = \dfrac{W}{t}$	work done over a whole interval
Instantaneous power	$P = Fv\cos\theta$	at one moment
Efficiency	$\eta = \dfrac{\text{useful output}}{\text{total input}}$	never greater than 1

When you use it

Use when a question gives you distances and speeds but no time, or asks how much fuel, food or electricity a job costs. The work and energy theorem is often a shortcut past the equations of motion, because it never asks how long anything took.

Watch out

A force at right angles to the motion does no work at all, so the tension in a string swinging a stone in a circle adds no energy however fast it goes. The cosine is what carries this, and dropping it is the commonest lost mark in the topic.

Turning motion read off straight line motionReference tables · v = s/t · a · +4

Straight line	Turning	What changes
$s$	$\theta$	metres become radians
$v = \dfrac{s}{t}$	$\omega = \dfrac{\theta}{t}$	$v = r\omega$
$a$	$\alpha$	$a = r\alpha$
$m$	$I = \sum mr^{2}$	mass becomes moment of inertia
$F = ma$	$\tau = I\alpha$	force becomes torque
$p = mv$	$L = I\omega$	momentum becomes angular momentum
$KE = \tfrac{1}{2}mv^{2}$	$KE = \tfrac{1}{2}I\omega^{2}$	the same energy, counted round an axis

When you use it

Use when a wheel, a disc or a rod turns about a fixed axis. Every equation you already know for straight line motion has a turning twin, so solve the rotating problem by writing the straight line one and swapping each quantity for its partner in this table.

Watch out

The angle must be in radians before any of the links between the two columns holds. A question given in degrees or in revolutions per minute has to be converted first, and forgetting that is what makes an answer come out a factor of 57 too large.

Moment of inertia of common bodiesReference tableThin rod, length L · Hoop or thin ring, radius r · Solid disc or cylinder, radius r · +2

Body	Axis	Moment of inertia
Thin rod, length $L$	through the centre, across the rod	$\tfrac{1}{12}mL^{2}$
Thin rod, length $L$	through one end, across the rod	$\tfrac{1}{3}mL^{2}$
Hoop or thin ring, radius $r$	through the centre, along the axis	$mr^{2}$
Solid disc or cylinder, radius $r$	through the centre, along the axis	$\tfrac{1}{2}mr^{2}$
Solid sphere, radius $r$	through a diameter	$\tfrac{2}{5}mr^{2}$
Hollow sphere, radius $r$	through a diameter	$\tfrac{2}{3}mr^{2}$

When you use it

Use whenever a torque question needs a number for I, or when two bodies race down a slope and you have to say which reaches the bottom first. The smaller the fraction, the closer the mass sits to the axis and the easier the body is to spin.

Watch out

Each of these belongs to one axis only. The same rod is three times harder to swing about its end than about its middle, and reading the wrong row is the usual error. For any other axis parallel to one of these, add $md^{2}$ , where d is the distance between the two axes.

The two conditions for equilibriumRule

\sum F = 0 \quad \text{and} \quad \sum \tau = 0

\sum F = 0 \quad \text{and} \quad \sum \tau = 0

$\sum F$: the sum of every force on the body, taken direction by direction $\mathrm{N}$
$\sum \tau$: the sum of every turning effect about any one chosen point $\mathrm{N\,m}$

When you use it

Use for a ladder against a wall, a beam on two supports, a signboard on a bracket: anything at rest or moving steadily. Both conditions must hold at once, which is what lets you find two unknown forces from one diagram.

Watch out

The first condition alone is not enough. Two equal and opposite forces applied at different points sum to zero and still spin the body, which is why a steering wheel turns. Take moments about the point where an unknown force acts and that force drops out of the equation, leaving one unknown to solve for.

Fluids at rest and in motionReference tablePressure · Pressure at a depth · Upthrust · +2

What you are finding	Formula	Conditions it holds under
Pressure	$P = \dfrac{F}{A}$	force at right angles to the area
Pressure at a depth	$P = \rho g h$	gauge pressure, fluid at rest
Upthrust	$F_{b} = \rho_{f}\,g\,V_{disp}$	$\rho_{f}$ is the FLUID's density
Flow rate stays equal	$A_{1}v_{1} = A_{2}v_{2}$	one pipe, nothing leaking out
Bernoulli	$P + \tfrac{1}{2}\rho v^{2} + \rho g h = \text{constant}$	steady flow, no viscosity

When you use it

Use for anything floating, sinking, or flowing through a pipe: a dam wall, a hydraulic jack, a boat, water speeding up through a narrow section.

Watch out

The density in the upthrust equation is the fluid's, not the object's, and the volume is the volume pushed aside rather than the whole object. A block half under water displaces half its own volume. Depth pressure also depends on depth alone, so a narrow tube and a wide lake at the same depth read the same.

Stress, strain and Young's modulusReference tableStress · Strain · Young's modulus · +2

What you are finding	Formula	Conditions it holds under
Stress	$\sigma = \dfrac{F}{A}$	force spread over the cross section
Strain	$\epsilon = \dfrac{\Delta L}{L_{0}}$	a ratio, so it has no unit
Young's modulus	$E = \dfrac{\sigma}{\epsilon}$	below the elastic limit only
Extension of a wire	$\Delta L = \dfrac{FL_{0}}{AE}$	same conditions as above
Energy stored	$U = \tfrac{1}{2}F\,\Delta L$	the work the stretch cost

When you use it

Use when a wire, cable or beam is stretched and the question asks how far it gives, how much load it will take, or which of two materials is stiffer.

Watch out

Young's modulus belongs to the material and not to the piece: a thick steel cable and a thin steel wire share one value of E, and it is the area in the equation that makes the thick one stretch less. Past the elastic limit the ratio stops being constant and none of these rows holds any more.

The same subject in other years

An exam paper keeps asking for what the year below taught. Those cards are here too.

Your other Grade 11 subjects

Everything else in this year that has cards so far.

Questions students ask

Is there a national exam in Grade 11?: No. Ethiopia sets national exams in Grade 6, Grade 8 and Grade 12 only. These cards are for your school's own exams, and for the national exam that comes a few years later.
Where do these cards come from?: They are written against the Ministry of Education textbook for Grade 11 Physics, and every formula, constant and table row is checked again before a card goes up.
Is this free?: Yes. Every card here is free to read and the printable sheet is free to download. Neither needs an account.
When was this last checked?: 6 September 2026. Cards arrive chapter by chapter, and the line under each one says when that card was last read through.

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