Physics · mechanics

Projectile Motion

Throw, launch or fire something and see where it lands.

Launch

aim & fire
20 m/s
45°
0 m
Quick scenarios

Trajectory

—
speed
Flight
Detail
How it works

Two motions at once

Two motions at once

Sideways at constant speed (nothing pushes it horizontally) and downward under gravity. Split the launch into v·cosθ and v·sinθ and solve each alone.

Range on level ground

R = v² sin 2θ / g. It peaks at 45° and is symmetric: 30° and 60° land in the same spot.

Height is vertical only

h = h₀ + (v sinθ)² / 2g. A steeper launch climbs higher but travels less far.

The frictionless ideal

No drag, no wind, no spin. Real projectiles, especially light or fast ones, fall short and steeper.

Worked example. Throw a ball at 20 m/s and 45° from ground level. It flies for 2.9 s, peaks at 10.2 m and lands 40.8 m away, hitting the ground at the same 20 m/s it left, just angled downward. On flat ground 45° gives the maximum range, and any two angles that add to 90° land in the same spot, as the bars show.
Field notes

What governs the flight

Split it in two

Horizontal and vertical motion are independent. Horizontal: constant speed v·cosθ. Vertical: starts at v·sinθ and slows, stops, then falls under gravity. Solve each separately, then combine.

Range

On level ground, R = v²·sin(2θ)/g. It peaks at θ = 45° and is symmetric: 30° and 60° reach the same distance. Launching from a height shifts the best angle lower.

Peak height

h = h₀ + (v·sinθ)²/(2g). Only the vertical component matters; a steeper launch climbs higher but travels less far.

× 6on the Moon

Range and hang time both scale as 1/g

Gravity there is about a sixth of Earth’s (1.62 against 9.81 m/s²), so the same throw goes about six times farther and stays up six times longer. Mass does not matter: without drag a cannonball and a pebble land together.

No air resistance

This model leaves out drag, so it overestimates range and height, sometimes a lot for light or fast objects. It is the clean physics-class ideal, useful for intuition rather than real ballistics. The golf mode on this page is the opposite case: it models drag and spin lift.

Questions

What people ask

Why does 45° go farthest?

Range depends on the product of horizontal speed and hang time. Lower angles have more horizontal speed but less hang time; higher angles the reverse. 45° balances them — on level ground. Launch from a height and the best angle drops below 45°.

Does mass matter?

Not here. Without air resistance, all projectiles follow the same path regardless of mass — a cannonball and a pebble launched identically land together. Add drag and that changes.

How wrong is "no air resistance"?

For dense, slow, heavy objects over short distances, barely. For light objects, high speeds, or long ranges, very — real range can be a fraction of the ideal. Treat this as the frictionless ideal.

What changes on the Moon?

Gravity is about ⅙ of Earth's, so the same throw goes roughly six times farther and stays up about six times longer. Switch the gravity buttons to see it.

How do I calculate the trajectory of a ball?

Split the launch into horizontal v·cosθ and vertical v·sinθ. At time t, x = v cosθ · t and y = h0 + v sinθ · t − ½ g t². Without air resistance the path is a parabola: at 20 m/s and 45° from the ground it flies for 2.9 s, peaks at 10.2 m and lands 40.8 m away.

Results are for reference only. This ignores air resistance — real projectiles fall shorter and steeper. Good for intuition, not ballistics.
Projectile Motion & Golf Ball Flight
  • Projectile modeThe ideal drag-free trajectory under constant gravity, split into independent horizontal and vertical motion, with range, peak height, flight time and impact speed from the standard kinematic equations.
  • AssumesNo air resistance, no wind, no spin or lift, flat level ground (except the launch height), and constant gravity. Wind is the one thing this mode has no input for at all.
  • Golf modeThe opposite case: a full 3D flight model that numerically integrates quadratic drag and Magnus-effect lift from your launch conditions, so air, spin and lift are all modelled, along with wind, altitude, lie, ball and surface.
  • Not forA learning and intuition tool, not for ballistic or safety-critical use.

Club & strike

pick one

Shot shape

Lie & ball

Conditions

No wind

Flight path

Driver t = 0.0 s
Tour
Reference flights
Landing

Bounce & roll out

—
speed
Flight result
Launch & shape
Reference

Club-by-club carry, under your current conditions

Adapts live to your wind, altitude, lie, ball and surface
ClubBall speedLaunchBackspinCarryTotalApex
Distribution

Where your swing sits among golfers

driver-equivalent ball speed · your selected club is scaled to a driver for comparison
Metric
Reference flights
How it works

Real aerodynamics, not a range-finder guess

Three forces

Gravity, drag opposing motion through the air, and Magnus lift, the force from spin that also curves a soccer free kick.

Backspin is lift

Backspin holds the ball up and extends carry. Tilt the spin axis off vertical and the same effect pulls it sideways into a draw or fade.

Integrated, not guessed

All three forces are integrated numerically in 3D (RK4): downrange, height and left/right curve.

Conditions change it

Wind, altitude, lie, ball and surface, or the Moon and Mars, each alter the drag and lift acting on the ball.

Worked example. A PGA Tour average driver swing (167 mph ball speed, 10.9° launch, 2,545 rpm backspin) carries 267 yards in this model with no wind at sea level, matching published Tour averages closely, then adds another 3 yards from two real bounces and a short roll-out for a 270-yard total. Tilt the spin axis 20° and the same swing curves about 35–40 yards offline by landing: a real slice or hook, not a cosmetic bend.
Field notes

What actually shapes a shot

Why one club can estimate your whole bag

Absolute numbers vary enormously between golfers; the ratios between clubs within one bag do not. Loft, shaft length and lie angle set those ratios, and they are much the same set of clubs for everyone. So if you know one club honestly, scaling the rest by the same speed factor lands close, usually within a few yards per club. What it cannot capture is a bag that is genuinely inconsistent: a driver you hit badly and a 7-iron you hit beautifully will produce an estimate that flatters one end and insults the other. Spin is scaled at reduced strength for the same reason, since spin follows loft and strike far more than speed.

What a percentile does and does not tell you

The distributions here describe populations. Being at the 60th percentile of average amateurs means 60% of that group swings slower; it says nothing about your handicap, because scoring is dominated by short game and course management, not speed. Plenty of single-figure players sit mid-pack on ball speed and beat people who out-drive them by 40 yards. Treat the curve as a speed benchmark, not a ranking of golfers.

Backspin vs. sidespin

Every real spin is a mix of the two: backspin (the dominant component, creating lift) and sidespin (the smaller component that curves the ball left or right). The “spin axis” slider here controls that mix: 0° is pure backspin, and larger tilts trade some lift for curve.

up to 1.5driver smash factor

Smash factor

Ball speed divided by clubhead speed, a measure of strike efficiency. A pure driver strike can approach 1.5; shorter, more lofted clubs sit lower (1.1–1.3) because more of the impact energy goes into spin and less into ball speed.

Spin ratio and lift

The lift coefficient here depends on the spin ratio: spin speed relative to ball speed, not spin rate alone. A driver’s high ball speed gives it a low spin ratio despite thousands of rpm, which is exactly why drivers are hit with far less backspin than wedges.

Why wedges climb steeper and fly less far

High loft trades ball speed for launch angle and spin: the same swing speed produces a slower, higher-spinning, steeply-climbing shot that trades distance for stopping power and control near the green.

Questions

What people ask

Why does backspin make the ball fly farther, not just higher?

Magnus lift fights gravity for longer, flattening the descent and extending the time the ball spends moving forward before it falls — up to a point. Too much spin (a "sky ball") adds height without adding distance, since the extra lift steepens the whole trajectory instead of extending it.

Why does rough reduce backspin?

Grass gets trapped between the clubface and the ball at impact — the "flyer lie" — reducing the friction that normally imparts spin. Less backspin means less lift and a lower, longer-rolling, less controllable shot, which is exactly why rough is harder to stop on the green from.

Why does altitude add distance?

Thinner air means less drag and less Magnus lift working on the ball — the classic "ball flies farther in Denver" effect. It also means slightly less lift, so very high-spin, high-altitude shots can fly a little flatter than expected even as they go farther overall.

How is the bounce and roll modelled?

Each bounce is a real, separately-integrated arc — vertical speed reflects off the surface at that surface's restitution (a lot of energy lost on sand or green, much less on hardpan), horizontal speed is cut by its friction, and the cascade repeats until the bounce height becomes genuinely negligible, followed by a decelerating roll-out. It's calibrated to realistic total distances, not a full contact-mechanics simulation — read individual bounce heights as illustrative, not laboratory measurements.

Why does the club table change when I adjust wind or altitude?

Every row recalculates under whatever conditions are currently set, using each club's own pro-average launch numbers — so the table always answers "how would each club do right now," not a fixed reference condition. If you've adjusted a club's own ball speed, launch or spin away from its pro average, the callout above the table compares your actual dialled-in shot to what a pro would get with that same club under those same conditions.

What changes on the Moon or Mars?

The Moon has no atmosphere at all — drag and Magnus lift both vanish entirely, wind is meaningless, and the ball follows a pure gravity-only arc at ⅙ Earth gravity (a real driver would sail for hundreds of yards). Mars keeps a thin CO₂ atmosphere — about 0.6% of Earth's sea-level pressure — so wind and altitude still matter, just far more weakly, on top of roughly ⅓ Earth's gravity.

Why does a golf ball fly farther than the projectile formula says?

For the Tour-average driver launch on this page (167 mph, 10.9°) the drag-free formula gives about 231 yards, while the simulated ball carries 267. Backspin gives the ball Magnus lift that outweighs the drag slowing it, so the vacuum range is a baseline, not a prediction.

Version history · 5 releases
  1. v0.532026-07-26Golf: fixed scales on all three views, skill slider, reference flights per level, and a landing-velocity bug that made descent angle and roll noise
  2. v0.542026-07-26Golf: masthead wrongly said "no drag", reference balls now fly, show-all toggle, slider no longer jumps, flight legend
  3. v0.552026-07-26Golf: colour-coded skill markers on every launch slider and the skill slider, and one colour language across the whole page
  4. v0.562026-07-26Golf: per-club slider ranges (no more superhuman spin), aim angle + Shot shape section, all-balls-fly toggle, fixed range width, marker alignment
  5. v0.572026-07-26Golf: 200 yd range with 50 yd markers, taller top view, slider markers now pixel-exact, level bar on a grid, all-fly moved to the flight views

Releases in which this page changed, newest last. Derived from the archived copy of every release, not from notes written afterwards — so it reflects what actually shipped. Site-wide passes are left out; they are in the full changelog.

Golf Ball Flight Simulator
  • Flight modelNumerically integrates (RK4) gravity, drag and Magnus-effect lift on a USGA-spec ball (45.9 g, 42.67 mm) in 3D. Drag coefficient varies mildly with speed (about 0.30 at wedge speeds down to about 0.205 at driver speeds, reflecting the Reynolds-number dependence of a dimpled sphere); lift follows the MacDonald–Hanzely fit against spin ratio.
  • Air and worldsAir density comes from temperature and altitude via the standard atmosphere model, or is fixed per world: the Moon (true vacuum, g = 1.62 m/s²) and Mars (thin CO₂ atmosphere, about 610 Pa base pressure, g = 3.71 m/s²).
  • ClubsPresets are calibrated to published PGA Tour average launch-monitor figures (ball speed, launch angle, backspin) and reproduce realistic average carry distances across the bag.
  • SimplifiedLie and ball-type effects are illustrative simplifications of well-documented real phenomena (flyer lies, cover-material spin differences). Landing-surface bounce and roll use a single representative bounce plus a rolling-friction roll-out, calibrated to realistic total distances rather than a full impact-mechanics model.
  • Not forA physics estimate for a clean, well-struck shot with a mid-handicap-to-Tour-average swing: not a substitute for a real launch monitor, and real shots vary with strike quality, equipment and technique far more than any of these sliders capture.

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