PhysicsUKProjectile lab

PROJECTILE MOTION · CUSTOM BUILDER

Your projectile experiment

Build it. Fire it. Measure what changes.

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Launcher A · next shot

Choose an investigation

Every investigation is editable. Switch to Custom to keep building the current experiment.

Experiment controls

Selected apparatus

Launcher edits apply to future shots. Other apparatus moves independently during a flight.

Environment

Display & measurement

Prediction ignores obstacles and is unavailable with air resistance. Arrow scales are separate; a force arrow is not a velocity arrow.

Save your experiment

Startup opens Custom. Save or restore an authored setup here.

Experiment notebook

Captured readings

Capture freezes a measured value and its launch/environment settings. Landed shots retain their impact readings.

Timing gates & impacts

Gates record the first crossing per projectile. Gate speed is an ideal instantaneous measurement. Targets catch downward crossings.

Investigate projectile motion

  1. Choose a question, change one variable and predict the result.
  2. Fire, pause or step. Read the graph and move instruments to measure.
  3. Capture readings or keep a run, change the variable and compare.
Build and operate

Drag a launcher to change its position, or its arrow tip to set the launch direction. Add more launchers for simultaneous comparisons. Drag a ledge corner to resize it, ruler endpoints to measure, or any instrument to move its sampling position. Edit gives precise numeric alternatives. Place at ledge edge is a one-time positioning action; it does not link the objects.

F: fire selected launcher · D: fire and drop · Space: run/pause · C: capture · arrows: move selected apparatus · Shift + arrows: fine move · Delete: remove · Enter: place · Escape: cancel. Shortcuts apply when the bench is focused. Pan with the Pan button or right/middle drag; wheel zooms around the pointer.

Firing and dropping

Horizontal firing and dropping from the same height, at the same instant, give the same fall time when air resistance is negligible. Both have the same initial vertical velocity, zero, and vertical acceleration −g. An angled launch has a different initial vertical velocity. Air resistance can also change the result. Fire + drop always uses the actual launch settings; it does not force the objects to land together.

Vectors, forces and measurements

Blue v is velocity; dashed vx/vy are its components. Green a is acceleration. Amber W is weight; purple D is drag; red F is the net force. Arrow scales are in Controls. In vacuum only weight acts during flight; at the apex vy is zero while acceleration remains downward. Force arrows stop at impact. Traces show measured history; equal-time dots mark the chosen interval. Graph curves use time since each projectile's release, making separate trials comparable.

Rulers read endpoint distance, Δx and Δy. Coordinate markers read x/y; protractors measure an angle from +x. Gate crossings and impact times are calculated at the apparatus's current geometry. Instruments are ideal and deterministic, with no simulated noise. Display values are rounded; exports retain numerical precision. Ruler ticks are one metre apart, with coarser ticks labelled on long rulers. Long trajectory records use coarser sampling to retain the whole flight within 2,400 samples; equal-time dots interpolate those samples. Restart clears current flights and events, preserving apparatus, captures and kept runs.

Physics model and limits

SI units; x right, y up, ground y = 0. Vacuum motion uses exact constant-acceleration steps. Optional quadratic drag uses Fd = −½ρCdA|v − w|(v − w), A = πd²/4, and numerical integration. Gravity, air density and horizontal wind are uniform. Cd is fixed per shot; no lift, spin, buoyancy, projectile collisions or bounce. Projectiles are points for contact; diameter determines drag area. Markers are enlarged for visibility.

Ledges are solid rectangles; targets catch downward crossings. A launched projectile retains its own properties when its launcher is moved. Live environment edits change future acceleration without rewriting previous motion. Moving apparatus is a geometry edit, not a collision with a physically moving surface. Predictions ignore obstacles and apply only to vacuum-to-ground motion. Shots stop at 120 s or the model bounds (−150 to 400 m horizontally, 180 m vertically).

Up to 16 moving projectiles, 48 retained flights, 40 apparatus objects and eight kept runs. Save/Open stores authored apparatus and environment, not a resumable flight or notebook. Hidden tabs pause; animation rate changes viewing time, not the physics. On a heavily loaded device, playback slows instead of jumping over the experiment.

Physics references

OpenStax: projectile motion · OpenStax: drag force. Inspired by hands-on investigations and PhET; original PhysicsUK implementation.