Newton's Laws of Motion Trivia
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99 free Newton's Laws of Motion trivia questions with answers — science & nature quiz, new questions added Oct 2026.
This Newton's laws of motion trivia quiz covers the three laws as a physics class teaches them and the history behind them. It starts with the laws themselves: the first law and inertia, the second law and the relationship between force, mass and acceleration, and the third law of action and reaction. Then it widens to the ideas the laws rest on, such as momentum, mass versus weight, friction, free fall, the newton as the SI unit of force, and why a rocket works in a vacuum. The easy questions ask which law explains why you lurch forward when a bus brakes and what the SI unit of force is called. The harder ones ask which book the laws first appeared in and in what year, who funded its printing, who coined the word 'inertia', which astronaut dropped a hammer and a feather on the Moon, and what Newton was doing at the Royal Mint. There is a short round on Isaac Newton himself: where he was born, when he was knighted and who he feuded with over calculus. If you want more, our physics and famous physicists quizzes continue the theme. Every answer was checked against the encyclopaedia entry for the law, the concept or the person before publishing, and the sentence that supports it is stored with each question.
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Q 01What closed Cambridge University in 1665, sending Isaac Newton home for two famously productive years?
The Great Plague
The Great Plague shut the university, and in less than two years at home Newton began the work on calculus, light and gravity that made his name.
Q 02A costly book on what stopped the Royal Society funding Newton's Principia?
Fish
Fish: the heavily illustrated De Historia Piscium sold so poorly that the Society could not pay for Newton's book, and it later settled one official's salary in unsold copies.
Q 03Newton's first law says a body's natural behaviour is to move how?
In a straight line at constant speed
In a straight line at constant speed: on a perfectly frictionless surface a sliding puck would simply never stop. Friction and air drag are what halt things on Earth.
Q 04According to Newton's first law, what is needed to change a body's state of rest or uniform motion?
A force impressed upon it
A force impressed upon it, in Newton's own words; and a change of direction counts, so a car rounding a bend at steady speed is being forced the whole way round.
Q 05When do bathroom scales in an elevator read more than your usual weight?
As it starts upward
As it starts upward: by Newton's second law the floor must push up harder than gravity pulls down to get you moving, and the scales read that push. At a steady speed the reading drops back to normal.
Q 06In modern terms, the net force on a body equals its mass multiplied by what?
Its acceleration
Its acceleration gives the famous F = ma, a formula that appears nowhere in Newton's Principia; it was in print by 1716, in Jakob Hermann's textbook Phoronomia.
Q 07When the net force on a body is zero, what is it said to be in?
Mechanical equilibrium
Mechanical equilibrium does not mean motionless: a parked car and one cruising dead straight at steady speed both qualify, because in each case the forces balance.
Q 08Newton's third law states that to every action there is always opposed what?
An equal reaction
An equal reaction, but the catch students miss is that the two forces act on different bodies, so they never simply cancel.
Q 09Newton's third law is related to which more fundamental principle?
Conservation of momentum
Conservation of momentum: in any push or collision, whatever momentum one body gains the other loses, so the total never changes.
Q 10In Newton's thought experiment, what does a cannonball fired fast enough from a mountaintop do instead of landing?
It circles the Earth
It circles the Earth: the ball never stops falling, but the ground curves away beneath it just as fast, which is how the Moon and every satellite stay up.
Q 11Linear momentum is the product of mass and what?
Velocity
Velocity, not plain speed, so the heading matters: two identical cars meeting head-on at the same speed have a combined momentum of exactly zero.
Q 12In SI units, momentum is measured in what?
Kilogram metres per second
Kilogram metres per second is simply mass times velocity spelled out; the same unit can be written as the newton second, a force multiplied by the time it acts.
Q 13Which ancient thinker taught that moving objects stop unless something keeps pushing them, a view that lasted nearly two thousand years?
Aristotle
Aristotle was describing what everyone sees: stop pushing a cart and it halts. Galileo and then Newton turned that around, arguing it is the stopping, not the moving, that needs a cause.
Q 21Inertial mass measures an object's resistance to what?
Being accelerated by a force
Being accelerated by a force: the more mass, the less a given push changes the motion, which is why a loaded trolley is so much harder to get going, and to stop, than an empty one.
Q 22A rocket engine produces thrust in accordance with which of Newton's laws?
The third law
The third law: the engine hurls hot gas backwards and the gas shoves the rocket forwards. It needs nothing behind it to push against, which is why rockets work best in a vacuum.
Q 23Friction is the force resisting what?
Relative motion of surfaces in contact
Q 14One newton accelerates a mass of one kilogram at what rate?
One metre per second squared
One metre per second squared: the unit was built from the second law itself, so one newton, one kilogram and that acceleration fit together with no conversion factor.
Q 15On Earth, about how many newtons does a one-kilogram bag of sugar weigh?
About 10
About 10: gravity pulls on every kilogram with 9.8 newtons. Bathroom scales really measure that force and merely display it as kilograms.
Q 16Force is what kind of quantity?
A vector
A vector: a force has a direction as well as a size, which is why two equal forces pulling one object in opposite directions add to nothing, as in a deadlocked tug of war.
Q 17How does an airbag cut the force on a passenger in a crash?
It lengthens the stop
It lengthens the stop: the passenger sheds the same momentum with or without the bag, but spread over a longer time the force is far smaller. Crumple zones work the same way.
Q 18Galileo worked out the idea behind Newton's first law by rolling balls along what?
Inclined planes
Inclined planes: a ball let go on one ramp climbs a facing ramp to nearly its starting height, so Galileo reasoned that on a level track it would simply roll on forever.
Q 19The word 'inertia' derives from a Latin word meaning what?
Idleness
Idleness: Kepler, who brought the word into physics, took rest to be the natural state, so inertia to him was a body's laziness about moving at all.
Q 20An astronaut on the Moon weighs a sixth of their Earth weight, but what happens to their mass?
It stays the same
It stays the same: mass is the amount of matter in a body, while weight is only how hard the local gravity pulls on it, and lunar gravity is about a sixth as strong.
Relative motion of surfaces in contact is what it resists, and it usually grips hardest before anything slides: once a heavy crate breaks free, it takes less push to keep it moving than it took to start.
Q 24Who discovered the classic laws of sliding friction around 1493, but never published them?
Leonardo da Vinci
Leonardo da Vinci scribbled them in a pocket notebook under a sketch of an old woman, and a museum director later dismissed the jottings as 'irrelevant notes'. The laws were found afresh two centuries on.
Q 25Which planet was found in 1846 only after mathematicians used Newton's laws to predict where it must be?
Neptune
Neptune: Uranus kept straying from its predicted path, so Urbain Le Verrier calculated where an unseen planet must be tugging at it, and a Berlin astronomer found it on his first night of looking.
Q 26Which detail of Newton's apple story was added by later storytellers?
It hit him on the head
It hit him on the head is the later embellishment. In 1726 Newton told his friend William Stukeley, over tea under some apple trees, only that a falling apple set him wondering why things always drop straight down.
Q 27When an Apollo astronaut dropped a hammer and a feather on the Moon, what happened?
They landed together
They landed together: with no air to hold it back, the falcon feather fell as fast as the geology hammer, just as Galileo had reasoned. David Scott did it live on television in 1971.
Q 28According to a possibly apocryphal tale, Galileo dropped objects from which landmark?
The Leaning Tower of Pisa
The Leaning Tower of Pisa story rests on one man's word: Vincenzo Viviani, the young pupil who worked beside the blind Galileo in his last years and became his first biographer.
Q 29Why was Galileo's last great book, on motion, printed in Holland and not Italy?
The Inquisition had banned him
The Inquisition had banned him from publishing anything, future works included, so Two New Sciences was spirited out of Italy and printed in Leiden in 1638. By then Galileo was blind and under house arrest.
Q 30Who encouraged and helped fund the publication of Newton's Principia?
Edmond Halley
Edmond Halley paid for the printing himself, then used Newton's laws to predict that the comet of 1682 would come back in 1758. It did, and it has carried his name ever since.