A pendulum hangs from a high dome and swings all day. Write the crowd working out what it is showing them.Fact: in 1851 a pendulum hung from a dome in Paris was used to demonstrate the rotation of the Earth.
Write the very bottom of a swing's arc as the wind in the rider's face.Angle: one instant, no longer than a blink. What is seen, heard and felt in it?
A car takes a corner at a steady speed and everyone leans. Write what changed, if the speed did not.Fact: when a vehicle turns, an acceleration occurs toward the new direction.
A ball is thrown, and this time the air matters. Write what the air does that the diagram left out.Fact: a baseball or a soccer ball makes drag in the air, so its flight is not strictly ballistic.
A ball is tossed straight up by someone riding a skateboard. Write where it comes down, and why the rider is not surprised.Fact: with no sideways force on it, a ball in flight keeps its sideways velocity.
A beach ball and a bowling ball are dropped on a world with no air. Write the race.Fact: in a vacuum all objects fall with the same acceleration, whatever their size, shape or weight.
A dropped ball bounces, bounces lower and bounces last. Write three short chapters.Angle: give each bounce fewer words than the bounce before it.
A juggler keeps three balls up. Write them as three overlapping stories, each with its own top.Angle: one is rising, one is at the top, one is falling. Stop the clock and describe all three.
A marble rolls off the edge of a table. Write the trip to the floor frame by frame.Fact: a projectile's motion splits in two: constant velocity sideways, steady acceleration downward.
A soccer ball bends around a wall of players. Write the bend as the air that was pushed aside.Fact: a spinning ball deflects the air to one side, and the ball reacts by moving the opposite way.
A sportscaster calls one high fly ball and leaves the physics in. Write the call.Angle: say when it stops rising. Say what is pulling it. Say who is under it.
In a snowball fight, describe every throw by its path and never by its target.Angle: flat and fast, or high and slow. Nobody says who got hit.
The same throw is made on the Moon. Write what the thrower notices first.Fact: gravitational acceleration on the Moon and on Mars is different from Earth's.
Slow one throw down. Write the ball's flight in five parts: the hand, the rise, the top, the fall, the catch.Fact: at the highest point of its flight, a ball's vertical velocity is zero.
Someone long ago rolls a ball down a shallow ramp, again and again, timing it. Write the afternoon the pattern shows.Fact: early experiments on falling used a ball on an inclined plane, and its velocity grew as it rolled down.
Tell the last second before a catch as the glove.Angle: the glove sees a dot become a ball. When does it know where to be?
Trace a ball thrown across a field as a line drawn on the sky. Write the shape, and who drew it.Fact: with air resistance left out, a thrown object follows a parabolic path.
Write the instant at the top of a throw, when the ball has stopped going up and has not started down.Fact: on Earth, gravity changes a ball's vertical velocity by 9.8 meters per second every second.
A ride on a wave 15
A bottle with a message in it bobs in the open ocean. Write why the waves keep passing and the bottle stays.Angle: every wave lifts it, circles it and sets it back. What finally moves it?
A calm lake at dawn receives its first pebble. Write what spreads.Angle: follow one ring outward. Describe the last one that can still be seen.
A stadium crowd does the wave. Write it as the one person who sees what is really moving.Angle: nobody leaves a seat, and still something goes all the way around.
A storm far out at sea sends a wave to a beach where the sun is shining. Write the wave's long trip.Fact: with nothing in its way, a wave can travel across an entire ocean basin.
A surfer waits between sets and reads the water. Write what she can tell before the wave arrives.Fact: most of the large breakers seen at a beach result from distant winds.
A wave pool has an opinion of the ocean. Write it.Angle: it makes the same wave on a timer and has heard the real ones never repeat.
A wave that crossed an ocean arrives as a slow, smooth swell. Write its speech on reaching the beach.Fact: waves that have left the wind that raised them are called swells and can travel thousands of kilometers.
Flick one end of a long jump rope and write the bump's run to the other end.Angle: the rope stays in your hands. The bump does not. What traveled?
Ride one wave from far out to the sand, and write it as the surfer.Fact: near the shore, waves grow steeper. A wave too steep and unstable becomes a breaker.
Three things decide how big a wave gets. Write them as three cooks arguing over one pot.Fact: wave height depends on wind speed, how long the wind blows, and fetch, the distance it blows over.
Write the birth of a wave as the wind that made it.Fact: wind-driven waves are created by friction between the wind and the surface of the water.
Write the moment a wave breaks, slowed down until it fills a page.Fact: a breaking wave is one whose base can no longer support its top, so it collapses.
Write the same wave as a seagull floating on it, who goes up, around and nowhere.Fact: waves carry energy, not water, across the ocean. The water itself moves in a circle.
Write the tide's complaint that people keep calling the wrong thing a tidal wave.Fact: tides are waves caused by the pull of the Moon and the Sun. A tsunami has little to do with tides.
Write the vocabulary lesson a wave gives a child on a beach: crest, trough and the distance between.Fact: wave height is measured from trough to crest, and wavelength from one crest to the next.
Faster, slower 15
A bus brakes hard. Write the stop as a backpack on the seat that keeps going.Fact: an object in motion stays in motion in a straight line unless an unbalanced force acts on it.
A car takes a corner at a steady speed and everyone leans. Write what changed, if the speed did not.Fact: when a vehicle turns, an acceleration occurs toward the new direction.
A car's speedometer tells the story of one trip to school. Write it.Fact: a speedometer shows instantaneous speed, the speed at one instant.
A feather and a coin are dropped in a classroom. Write the race, and then the same race with the air taken away.Fact: all free-falling objects fall at the same rate only in a vacuum, where there is no air resistance.
A raindrop and a hailstone leave the same cloud. Write the fall of each and what the air had to say.Angle: the air pushes back on both. Write it as a conversation on the way down.
A rocket leaves the pad slowly and is soon very fast. Write its first ten seconds, one to a sentence.Fact: a force causes a change in velocity, and the acceleration is proportional to the size of the force.
A skydiver falls faster and faster, and then does not. Write the moment the speeding up stops.Fact: when drag equals weight, a falling object stops accelerating and falls at its terminal velocity.
A sprinter and a loaded truck leave the same line when the light turns green. Write the first three seconds.Fact: for equal forces, a heavier object accelerates less than a lighter one.
Slowing down is a kind of acceleration too. Write a physicist explaining that to a driver at a stop sign.Fact: physics treats speeding up and slowing down the same way. Both are changes in velocity.
Tell a bicycle ride in three sentences: speeding up, holding steady, slowing down. Then say which one felt like nothing.Fact: with no net force on it, an object keeps a constant velocity.
Think of the slowest moving thing you can. Give it one whole paragraph.Angle: a shadow crossing a floor, a glacier, a plant turning. Find the verb for almost not moving.
Write a race between a snail and a jet, judged by someone who cares only about change of speed.Angle: the jet is cruising. The snail has just set off. Who is accelerating?
Write a runner's hundred meters as her average speed and her top speed arguing over the medal.Fact: average speed is the distance traveled divided by the time it took.
Write an elevator ride as the feeling in your stomach, floor by floor.Fact: a person in an elevator feels heavier or lighter as it speeds up or slows down.
Write the opening of a parachute as the air that suddenly has more to push on.Fact: a parachute, with a large area for its mass, has a lower terminal velocity than a dart.
Back and forth 15
A child pumps a swing higher with legs alone. Write how, for someone who has never seen a swing.Angle: say when the legs go out and when they tuck in. Why does the timing matter?
A pendulum clock is carried far from home and starts to disagree with the clocks it left. Write the clock's defense.Fact: a pendulum's period depends on the local strength of gravity as well as on its length.
A pendulum hangs from a high dome and swings all day. Write the crowd working out what it is showing them.Fact: in 1851 a pendulum hung from a dome in Paris was used to demonstrate the rotation of the Earth.
A small child and a grown-up sit on swings of the same length. Write who gets back first.Fact: a pendulum's period depends on its length and is independent of the mass of the bob.
A spider hangs on a thread and reels itself in as it swings. Write what happens to the swinging.Fact: the period of a simple pendulum depends on its length.
A swing is left alone and slowly comes to rest. Write its last few passes.Angle: each is a little smaller. Write the one you cannot be sure you saw.
A tire swing has a year: who sat on it each season, and how high each one went. Write it.Angle: spring, summer, fall, winter. The rope is the same length all year.
At the very top of the arc the swing stops for no time at all. Write that instant.First line: For an instant nothing moved, and then everything started back the other way.
The pendulum in a tall clock is about as long as a walking stick. Write the clockmaker explaining why.Fact: a grandfather clock's seconds pendulum is about 1 meter long, and each swing takes one second.
Slow one pass of a playground swing down. Write it in four parts: back, down, up and the pause.Fact: a pendulum is a weight hung from a pivot so that it can swing freely.
Someone in a cathedral watches a hanging lamp swing and wonders how long each swing takes. Write the idea arriving.Fact: by one account, the first study of pendulums was sparked by a chandelier swinging in a cathedral.
Write a duet for two pendulums of different lengths that agree only once in a while.Angle: one is quick, one is slow. Describe the moment they line up, and how soon it is lost.
Write a grandfather clock's opinion of the phone that replaced it.Fact: in the 18th and 19th centuries the pendulum clock was the most accurate timekeeper.
Write a wide swing and a narrow swing of the same pendulum racing each other.Fact: for small swings, a pendulum's period is about the same whether the swing is wide or narrow.
Write the very bottom of a swing's arc as the wind in the rider's face.Angle: one instant, no longer than a blink. What is seen, heard and felt in it?
How it works
A physics writing prompt here takes one moving thing, slows it down and asks for each part: the rise, the top, the fall. Facts come from NASA's Glenn Research Center, NOAA's National Ocean Service and Wikipedia.
Read the full guide
Slow one moving thing down
A thrown ball gets fifteen prompts and a wave fifteen more. One asks for a throw in five parts, from the hand to the catch. Another follows a storm's wave across an ocean to a beach where the sun is shining. The facts say what gravity, the air and the wind are each doing.
Faster, slower, back and forth
Fifteen prompts are about a change of speed: a skydiver who stops speeding up, a backpack that keeps going when the bus brakes. The last fifteen swing: a playground swing in four parts, the pendulum of a tall clock, a spider reeling in its thread.
Pick the instant, then stretch it. Half a second can take a page.
Name the force once, plainly, and go back to what it feels like.
Questions and answers
What is a good physics writing prompt?
One small enough to watch. A marble rolls off the edge of a table. Write the trip to the floor frame by frame. The fact under it says the motion splits in two: steady sideways, speeding up downward.
Does a heavier object fall faster?
Not in a vacuum. NASA's Glenn Research Center says all objects free fall with the same acceleration, whatever their size, shape or weight. In air, drag changes that. One prompt drops a feather and a coin twice, with the air and without.
Why does a pendulum keep time?
For small swings, each one takes about the same time whether it is wide or narrow, and that time depends on the pendulum's length, not on the weight at the end. In the 18th and 19th centuries no clock was more accurate.