Projectile Motion Classroom Activity, 40 Minutes

Run a 40 minute lesson in four blocks: a 5 minute hook, 25 minutes of guided exploration on the projectile launcher where students predict a reading before every change, a 5 minute check for understanding, and a 5 minute exit ticket. A no-tech variant swaps the launcher for a tossed ball.

AP Physics: Unit 1 (topics 1.5 Vectors and Motion in Two Dimensions). Built for AP Physics 1 Unit 1, Topic 1.5, Vectors and Motion in Two Dimensions, which carries 10 to 15 percent of the multiple-choice section. The predict-then-reveal structure targets EK 1.5.B.1, that two-dimensional motion can be analyzed by separating it into one-dimensional components.

Lesson at a glance

Essential question: if nothing pushes a launched object forward, why does it keep moving forward the whole time it falls?

This lesson targets Topic 1.5, Vectors and Motion in Two Dimensions, in Unit 1 of AP Physics 1, worth 10 to 15 percent of the multiple-choice section. Students should already know the three constant-acceleration kinematic equations in one dimension before this lesson; if that is shaky, run kinematic equations first.

Block	Minutes	Purpose
Hook	5	Surface the forward-push misconception before naming it
Guided exploration	25	Predict, then reveal, on the projectile launcher
Check for understanding	5	Fast formative check, whole class
Exit ticket	5	Individual, collected

By the end, students should be able to state that horizontal velocity stays constant across the whole flight, that vertical velocity changes at a constant rate, and that the range-maximizing angle of 45 degrees only holds when the object lands at the same height it launched from.

Materials

A projector or one device per pair, open to the projectile launcher
Scratch paper or a mini whiteboard per student, for writing a prediction before each reveal
The exit ticket questions below, printed as a half sheet or posted for students to answer on paper
For the no-tech variant: a soft ball or bean bag, a stopwatch or phone timer, and a meter stick or measuring tape

No sign-up, login, or install is required. The simulator runs in the browser and every reading it shows is computed live from the same launch angle, speed, height, and gravity you set on screen.

Hook: what keeps it moving forward? (5 minutes)

Toss a soft ball or a wadded piece of paper in a gentle arc across the room, catching it at roughly the height you threw it from. Do it two or three times.

Ask the room to vote with a show of hands on one question: while the ball is in the air, is anything still pushing it forward? Do not resolve the vote yet. Write the two positions on the board exactly as students phrase them, typically something like "your hand pushed it, then it just carries the push" against "nothing is pushing it, it is just still moving."

Tell the class you built a tool that draws the actual forward speed and the actual falling speed separately, frame by frame, and that it will settle the vote in the next twenty five minutes. Do not give the answer here. The unresolved vote is what makes the first guided-exploration move land.

Guided exploration on the projectile launcher (25 minutes)

Open the projectile launcher on the projector at its starting values: 45 degree angle, 20 m/s launch speed, 0 m launch height, Earth gravity. Each move below has a prediction step before you touch a control. Cold-call for the prediction, then make the change and read the number out loud.

Baseline reveal. Before touching anything, ask: at 45 degrees and 20 m/s from the ground, how far do you think this lands, and how high does it go? Take two or three guesses, then read the Range and Max height readouts: about 41 m and about 10 m, with a 2.9 s flight. Ask which guesses were closest and why those students picked those numbers.

Same speed, smaller angle. Predict: if I drag the launch angle down to 30 degrees and leave speed at 20 m/s, does the range go up, down, or stay the same? Most classes split. Drag the angle slider to 30. Reveal: range drops to about 35 m. Ask what happened to the flight time on the readout row, and why a lower arc might travel less far even though the launch speed did not change.

The complementary pair. Predict again: now I raise the angle to 60 degrees, past 45. Does the range go up from the 30 degree result, down, or land in the same place? Set the slider to 60. Reveal: range is about 35 m again, matching the 30 degree case almost exactly. Name the pattern: 30 and 60 add to 90, and any two angles that add to 90 degrees produce the same range when launch and landing height match. Ask a student to guess what 20 and 70 would do before you check it.

Height enters. Reset the angle to 45. Predict: if I raise the launch platform to 10 m, using the height slider, and keep the same speed and angle, does the range increase, decrease, or stay near 41 m? Set height to 10. Reveal: range grows to about 49 m. Ask why, and steer the answer toward hang time: the extra 10 m of fall adds time in the air for the same forward speed to cover ground, for free.

Beat 45 from the platform. Stay at height 10 m. Predict: with the platform raised, is 45 degrees still the single best angle for distance, or could a shallower angle now win? Test it live: set the angle to 35 degrees at the same speed and height. Reveal: range comes out slightly ahead of the 45 degree result, around 49.5 m versus 49.1 m. The best angle shifted below 45 the moment launch height became greater than landing height.

Switch worlds. Reset height to 0 and angle to 45. Predict: on the Moon, where gravity is about 1.6 m/s squared instead of 9.8, does the same launch fly a little farther or a lot farther? Click the Moon button in the gravity control. Reveal: flight time jumps to nearly 18 seconds and range to roughly 250 m, over six times the Earth range from an identical launch. Ask what that implies about why a lower-gravity world needs a much bigger field to play the same game.

Read the components, not just the summary. Switch gravity back to Earth. Use the launch, apex, and landing buttons under the time scrubber. At launch, read v_x and v_y off the readout row: both equal, about 14.1 m/s, since the angle is 45 degrees. At apex, read them again: v_y has dropped to 0, but v_x still reads about 14.1 m/s, unchanged. That is the answer to the hook. Nothing pushes the object forward after launch, and nothing needs to; the horizontal component simply never had a force acting on it to begin with, so the readout never moves. Only the vertical component, driven by gravity, changes.

Rerun the vote. Click landing. At height 0 the v_y readout returns to about negative 14.1 m/s, the mirror of the launch value. Raise the height slider back to 10 m and click landing again: v_y is now a larger negative number, since the object fell farther than it rose. Take the hook's forward-push vote again by a show of hands. It should flip to "nothing is pushing it" once the class has watched v_x sit still through every one of these moves. Note out loud that the replay-flight button is a visual animation only; it does not compute anything new, so keep using the scrubber and the readout row to get numbers.

Check for understanding (5 minutes)

Fast, whole class, thumbs up or down or a one-word shout, no writing required:

True or false: at the exact top of the arc, the object's velocity is zero. (False. Only the vertical component is zero; the horizontal component is unchanged from launch.)
A ball launched at 20 degrees and one launched at 70 degrees, same speed, same ground level start and landing. Same range or different? (Same range; 20 and 70 add to 90.)
A drone launches a package at 45 degrees from a rooftop above the delivery point. Is 45 degrees still the farthest-reaching angle, or would a flatter angle send the package farther? (A flatter angle wins once the launch point is higher than the landing point.)

If more than a few thumbs go the wrong way on question 1, rerun move 7 before moving on. That one move carries the whole lesson.

Exit ticket (5 minutes)

Individual, on paper, collected at the door:

A ball is launched from ground level and lands at ground level. At the highest point of its flight, what is true about its vertical velocity? What is true about its horizontal velocity? Explain the difference in one or two sentences.
A cannonball fired at 25 degrees and one fired at 65 degrees, same speed, both from and to ground level, land in the same spot. Explain why using the word "complementary."
A slingshot on a cliff edge fires at 45 degrees toward the flat ground far below. Would lowering the angle below 45 degrees increase or decrease the range? Answer in one sentence using the idea of hang time.

Score questions 1 and 3 as understood or not yet; question 2 as correct use of "complementary" or not. A class where most students get question 1 but miss question 3 is ready for practice problems; a class that misses question 1 needs move 7 repeated before independent work.

No-tech variant

Run the same four blocks with a tossed ball instead of the screen, useful for a room with no projector or when devices are the distraction rather than the tool.

Pairs get a soft ball and a stopwatch. One partner tosses the ball straight up from shoulder height and catches it at the same height; the other times the full flight. Because the toss starts and ends at the same height, the time to the peak is exactly half the total flight time, so students compute v_y at launch from v_y = g times the time to the peak, using g = 9.8 m/s squared. A 1.0 second total flight gives a 0.5 second rise, so v_y = 9.8 times 0.5, about 4.9 m/s.

For the angle-and-height moves that the on-screen simulator handles by dragging a slider, hand out a printed card with three preset results computed ahead of time: 45 degrees and 20 m/s from the ground, the same launch from a 10 m platform, and the same launch on the Moon at g = 1.6. Students record their prediction on paper first, then flip the card over to check the number, matching the predict-then-reveal structure of moves 1, 4, and 6 above without any screen at all.

The complementary-angle move (move 3) still needs no equipment: toss the same ball twice at a visibly shallow arc and a visibly steep arc so it travels the same distance both times, and ask students to explain why using only their eyes and the vote from the hook.

Common misconceptions

Horizontal and vertical independence. The most common error is treating the object's overall speed as one number that just "runs out" going up and "comes back" going down. The launcher's readout row splits every reading into v_x and v_y specifically to break that habit: v_x is the same number at launch, at the apex, and everywhere in between, because nothing in the simulation ever pushes the object sideways after it leaves the platform. Only v_y changes, and it changes at a constant rate set by gravity. If a student says the object "slows down" near the top, ask which component they mean; the honest answer is only v_y.

The 45 degree myth, two different reasons. Textbooks often state that 45 degrees always maximizes range, and two separate corrections apply. First, this simulator, like the algebra behind it, has no air resistance; it is not modeling drag, so it cannot be used to argue that real thrown balls or shells behave exactly this way once air resistance is added; a real projectile with meaningful drag reaches its farthest range at an angle below 45 degrees, but that effect is outside what this tool computes. Second, and fully demonstrable inside the simulator without adding air resistance at all, launch height alone breaks the 45 degree rule, as move 4 and move 5 above show directly: raise the platform above the landing plane and a shallower angle outranges 45 degrees, because the extra height buys hang time that a flatter, faster-forward-moving launch can spend more efficiently. Keep those two reasons separate when a student brings up one while you are demonstrating the other.

What happens at the apex. Students frequently say the object "stops" at the top of its arc. It does not. Only v_y reaches zero, for a single instant, and v_x is unaffected and nonzero the entire time (unless the launch angle is 90 degrees, past this simulator's 85 degree maximum, in which case v_x is zero throughout the whole flight, not only at the apex). The acceleration due to gravity never reaches zero either; it stays constant at whatever the gravity control is set to, including at the exact moment v_y passes through zero. A useful test question: ask what the acceleration is at the apex, and expect the wrong answer "zero" until move 7 has been discussed.

The baseline reveal: 45 degrees at 20 m/s

Move 1 of the guided exploration opens the projectile launcher at its starting values: 45 degree angle, 20 m/s launch speed, 0 m launch height, Earth gravity. Before reading the readouts, find the range, the maximum height, and the time of flight by hand. Use $g = 9.8 \text{ m/s}^2$ and ignore air resistance, the same assumptions the simulator itself uses to compute every number it displays.

Break the launch velocity into components. At 45 degrees, $v_{x0} = v_{y0} = 20 \cos 45^\circ = 20 \sin 45^\circ = 14.14$ m/s.
Time of flight: the launch height is 0, so the object lands at launch height and the rise time equals the fall time. $t = \frac{2 v_{y0}}{g} = \frac{2(14.14 \text{ m/s})}{9.8 \text{ m/s}^2} = 2.89$ s.
Range: since $v_{x0} = v_{y0}$ at 45 degrees, $R = v_{x0} t = \frac{2 v_{x0} v_{y0}}{g} = \frac{2(14.14 \text{ m/s})^2}{9.8 \text{ m/s}^2} = \frac{399.9}{9.8} = 40.8$ m.
Maximum height: at the top of the arc $v_y = 0$ , so $H = \frac{v_{y0}^2}{2g} = \frac{(14.14 \text{ m/s})^2}{2(9.8 \text{ m/s}^2)} = \frac{199.9}{19.6} = 10.2$ m.

Time of flight 2.89 s, range 40.8 m, maximum height 10.2 m, matching the simulator's own readouts of about 2.9 s, 41 m, and 10 m from move 1's baseline reveal. Every later move in the guided exploration compares its result back to these three numbers.

Frequently asked questions

How long does this projectile motion activity take?

40 minutes as written: a 5 minute physical hook, 25 minutes of guided exploration on the projectile launcher, a 5 minute check for understanding, and a 5 minute exit ticket. Trim a guided-exploration move or two to fit a 30 minute block, or add a ninth move testing the Mars gravity button (g = 3.7 m/s squared) as a third world alongside the Earth and Moon comparison from move 6, to stretch it toward a full period.

What do students need to know before this lesson?

The three constant-acceleration kinematic equations in one dimension, and the idea that acceleration due to gravity is a constant 9.8 m/s squared on Earth. If either is shaky, run kinematic equations first, since this lesson applies those same equations separately to the x and y directions rather than reteaching them.

Does the projectile launcher simulator include air resistance?

No. It computes position and velocity from the constant-acceleration kinematic equations only, with gravity as the sole force after launch. That is exactly why it can cleanly demonstrate the launch-height effect on the best angle (move 4 and move 5), but it cannot be used to demonstrate the separate, real effect that air resistance has on optimal launch angle; flag that distinction explicitly when the 45 degree question comes up.

How do I run this without a projector or student devices?

Use the no-tech variant: a tossed ball, a stopwatch, and a printed card of three preset results (ground level, a 10 m platform, and Moon gravity) that students flip over after writing a prediction. It keeps the same predict-then-reveal structure as the on-screen version for the height and gravity moves, and the complementary-angle move works from a visible toss with no equipment at all.

What is the single most important move if I only have time for one?

Move 7, reading v_x and v_y separately at launch and at the apex. Watching the horizontal reading hold perfectly still while the vertical reading drops to zero is what actually resolves the hook's forward-push vote; every other move builds on that same split readout.