Acceleration Converter

Quick Reference Table

From	To	Multiply By	Example
g-force (g)	m/s²	9.80665	1 g = 9.81 m/s²
m/s²	g-force	0.101972	9.81 m/s² = 1 g
g-force (g)	ft/s²	32.174	1 g = 32.17 ft/s²
ft/s²	m/s²	0.3048	32.17 ft/s² = 9.81 m/s²
Gal (cm/s²)	m/s²	0.01	100 gal = 1 m/s²
m/s²	Gal	100	1 m/s² = 100 gal
ft/s²	g-force	0.031081	32.17 ft/s² = 1 g
km/h/s	m/s²	0.277778	100 km/h/s = 27.8 m/s²

Common Acceleration Values

Description	m/s²	g-force	ft/s²
Earth gravity (standard)	9.80665	1.0	32.174
Moon gravity	1.62	0.165	5.32
Mars gravity	3.71	0.378	12.17
Human walking	~2	~0.2	~6.6
Car 0-60 mph (4 sec)	~6.7	~0.68	~22
Sports car (aggressive)	~12-15	~1.2-1.5	~39-49
Roller coaster	~29-39	~3-4	~95-128
Fighter jet (sustained)	~78	~8	~256
Space shuttle launch	~29	~3	~95
Apollo 16 reentry (peak)	~64	~6.5	~210
F1 car braking	~49	~5	~161

Understanding Acceleration Units

Meters per Second Squared (m/s²)

Definition: The SI unit of acceleration. Represents the change in velocity (in meters per second) per second. If an object accelerates at 1 m/s², its velocity increases by 1 m/s every second.

History: Derived directly from SI base units (meter and second). Established with the metric system as the standard scientific unit for acceleration.

Current Use: Universal scientific standard for measuring acceleration. Used in physics, engineering, vehicle specifications, and scientific research worldwide. Seismology uses m/s² for earthquake ground motion. Standard gravity is defined as 9.80665 m/s² at sea level.

g-force (g or G)

Definition: A relative measure of acceleration expressed as a multiple of standard Earth gravity (9.80665 m/s²). 1 g = standard gravitational acceleration. 2 g means twice Earth's gravity, etc. Can be positive (acceleration) or negative (deceleration).

History: Emerged in early aviation and aerospace to describe forces experienced by pilots and astronauts relative to normal Earth gravity. Term "g-force" popularized in 1950s-1960s space race era.

Current Use: Aviation and aerospace for describing forces on pilots and passengers. Automotive testing (0-60 mph times, cornering forces). Amusement park ride specifications. Centrifuge ratings in medical and industrial applications. Sports science for impact analysis. Fighter pilots can withstand 9 g briefly with g-suits; untrained humans lose consciousness around 4-6 g sustained.

Feet per Second Squared (ft/s²)

Definition: Imperial unit of acceleration. Change in velocity (feet per second) per second. Standard gravity = 32.174 ft/s². If accelerating at 1 ft/s², velocity increases by 1 ft/s every second.

History: Imperial measurement derived from foot and second units. Used historically in American and British engineering.

Current Use: Used in United States for some engineering applications, ballistics calculations, and older physics textbooks. Gradually being replaced by m/s² even in US scientific contexts. Still appears in American engineering standards and automotive specifications.

Gal (Galileo)

Definition: CGS (centimeter-gram-second) unit of acceleration. Equal to 1 cm/s² or 0.01 m/s². Named after Galileo Galilei. 1 gal = 0.01 m/s².

History: Established in CGS system around 1900. Named in honor of Galileo Galilei who made fundamental discoveries about acceleration and motion in the early 1600s.

Current Use: Primary unit in geophysics and seismology for measuring seismic vibrations and gravitational field variations. Earthquake ground motion commonly measured in gal. Gravimetry (measuring variations in Earth's gravitational field) uses milligal (0.001 gal). Not commonly used outside these specialized fields.

Kilometers per Hour per Second (km/h/s)

Definition: Change in velocity measured in kilometers per hour, occurring over one second. Equal to 0.277778 m/s². Intuitive for automotive acceleration.

History: Practical unit that emerged with automotive industry using km/h for speed.

Current Use: Sometimes used informally in automotive contexts in countries using metric speeds. More intuitive than m/s² for describing car acceleration for general public. Not a standard scientific unit but appears in automotive journalism and marketing.

Miles per Hour per Second (mph/s)

Definition: Change in velocity in miles per hour per second. Equal to 0.44704 m/s². Common in US automotive contexts.

History: Emerged with American automotive industry and speed measurements in mph.

Current Use: Used informally in United States for describing vehicle acceleration. Car reviews often state "0-60 mph in 4 seconds" which implies average acceleration of 15 mph/s or ~6.7 m/s². Not a formal scientific unit.

Knot per Second (kn/s)

Definition: Change in speed of one nautical mile per hour per second. Equal to 0.514444 m/s². Used in maritime and aviation contexts.

History: Derived from nautical speed measurements.

Current Use: Aviation for describing aircraft acceleration during takeoff. Maritime applications. Flight simulators. Not commonly used outside aviation/maritime contexts.

Frequently Asked Questions

What is 1 g-force in m/s²?

1 g-force equals exactly 9.80665 m/s² (standard gravity). This is the acceleration due to Earth's gravity at sea level. To convert g-force to m/s², multiply by 9.80665. Example: 3 g × 9.80665 = 29.42 m/s². This means 3 g acceleration is three times as strong as Earth's gravity.

How many g's can a human survive?

Depends on duration and direction: Horizontal (forward): 20+ g for brief moments (car crash), 6-8 g sustained (with training). Vertical (head-to-feet): 4-6 g causes blackout in untrained people; 9+ g with g-suit for trained pilots. Upward (feet-to-head): More dangerous, 2-3 g can cause "redout". Formula 1 drivers experience 5-6 g in corners. Fighter pilots can sustain 9 g briefly. Astronauts experience 3-4 g during launch.

What is the acceleration of a car from 0-60 mph?

Depends on time: 6 seconds (typical): ~4.5 m/s² or 0.46 g. 4 seconds (fast): ~6.7 m/s² or 0.68 g. 3 seconds (very fast): ~8.9 m/s² or 0.91 g. 2.5 seconds (supercar): ~10.7 m/s² or 1.09 g. Formula: acceleration = (60 mph ÷ 2.237 m/s per mph) ÷ time in seconds.

What is the difference between acceleration and velocity?

Velocity is how fast something moves (speed with direction): 50 mph, 20 m/s. Acceleration is how quickly velocity changes: 5 m/s², 2 g. Example: Car traveling at constant 60 mph has zero acceleration. Car speeding up from 0-60 mph has positive acceleration. Car braking has negative acceleration (deceleration). Turning at constant speed involves acceleration (direction change).

Why do astronauts experience 3 g during launch?

Rockets must accelerate to orbital velocity (~28,000 km/h or 17,500 mph) to reach orbit. This requires sustained acceleration of about 3 g (29.4 m/s²) for several minutes. Higher g-forces would be unsafe for extended periods. Shuttle limited to 3 g max for crew safety. Modern rockets design profiles to balance speed requirements with crew safety, keeping acceleration under 4 g.

What is centripetal acceleration?

Acceleration toward the center when moving in a circle, even at constant speed. Formula: a = v²/r (velocity squared divided by radius). Example: Car turning a corner at 30 mph (13.4 m/s) with 20m radius: a = 13.4²/20 = 8.98 m/s² or 0.92 g. This is why you feel pushed outward in turns—your body wants to go straight while the car accelerates inward.

How is earthquake acceleration measured?

Seismologists use gal (1 cm/s²) or m/s². Peak Ground Acceleration (PGA) measures maximum acceleration during earthquake. Weak shaking: 10-100 gal (0.1-1 m/s²). Moderate: 100-500 gal. Strong: 500+ gal. Extreme: 1000+ gal (10+ m/s²). Magnitude measures energy; acceleration measures ground shaking intensity at a location. Same magnitude can produce different accelerations depending on distance and geology.

What acceleration do roller coasters produce?

Most coasters: 3-4 g peak (safe for healthy riders). Intense coasters: 5-6.5 g briefly. Record holder: Tower of Terror II in Australia briefly hit 6.5 g. These forces are carefully controlled—sustained high g's would be dangerous. Typical coaster: 3 g on loops, 1-2 g on hills, brief negative g's (weightlessness) on drops. Safety limits: 6 g positive, -2 g negative.

Common Uses for Acceleration Conversion

• Automotive: Converting vehicle acceleration specs and performance data
• Aviation: Understanding g-forces on pilots and passengers
• Aerospace: Calculating launch and reentry forces
• Physics Education: Solving kinematics problems
• Seismology: Converting earthquake acceleration measurements
• Sports Science: Analyzing impact forces in athletics
• Engineering: Structural analysis and crash testing
• Ride Design: Ensuring amusement park safety

Acceleration Conversion Tips

1. Remember Earth gravity: 1 g = 9.81 m/s² = 32.17 ft/s²
2. Quick g conversion: Divide m/s² by ~10 for approximate g's
3. Car acceleration estimate: 0-60 in 6 sec ≈ 0.5 g
4. Direction matters: Forward/back, up/down affect human tolerance
5. Negative g = deceleration: Braking produces negative acceleration
6. Gal in seismology: 1 gal = 1 cm/s² = 0.01 m/s²
7. Use proper notation: m/s² (not m/s/s), g (lowercase for g-force)

Interesting Acceleration Facts

• Flea jump: ~100 g (one of nature's highest accelerations)
• Mantis shrimp punch: ~10,400 g (fastest acceleration in animal kingdom)
• Baseball bat hitting ball: ~3,000 g
• Bullet leaving gun: ~20,000-30,000 g
• Air bag deployment: ~60 g over 36 milliseconds
• Ejection seat: 12-14 g (survivable but uncomfortable)
• Formula 1 crash: Can exceed 100 g briefly (Romain Grosjean 2020: 67 g, survived)
• Space shuttle landing: ~1.7 g (gentle compared to launch)
• Strongest earthquake recorded: ~4 g horizontal acceleration (Kobe 1995)
• Saturn V rocket: Max 4 g during first stage
• Top Thrill Dragster coaster: 0-120 mph in 3.8 sec (1.43 g average)
• Gravitron ride: Up to 3 g sustained for minutes
• Human sneeze: Head accelerates at ~10 g

Acceleration in Different Contexts

Automotive Performance

Economy car: 0.3-0.4 g (0-60 in 9-11 sec). Sports sedan: 0.5-0.7 g (0-60 in 5-6 sec). Sports car: 0.8-1.0 g (0-60 in 3-4 sec). Supercar: 1.0-1.5 g (0-60 in 2-3 sec). Dragster: 4-5 g (0-100 in 1 sec). Braking typically produces 0.7-1.0 g for most cars.

Aviation

Commercial takeoff: 0.2-0.3 g. Turbulence: 0.5-2 g (severe). Fighter jet maneuvers: 7-9 g. Airshow aerobatics: 10-12 g (brief). Pilot training: Practice 6-7 g sustained. G-suits help pilots tolerate higher forces by preventing blood pooling in legs.

Space Travel

Shuttle launch: 3 g max. Soyuz launch: 3.5-4 g. Apollo reentry: 6-7 g. Gemini emergency abort: 8 g designed (never used). SpaceX Dragon: ~4 g max. Atmospheric reentry most intense phase. Astronauts train extensively for g-forces.

Natural Forces

Earth's gravity: 1 g (9.81 m/s²). Moon: 0.165 g. Mars: 0.38 g. Jupiter: 2.53 g. Sun: 28 g at surface. Neutron star: billions of g's. Black hole event horizon: extreme g-forces (varies by mass).

G-Force Effects on Humans

Positive G (Head to Feet)

1-2 g: Tolerable indefinitely, slight heaviness. 3-4 g: Difficult to lift arms, tunnel vision starts. 5-6 g: Vision loss (greyout/blackout), breathing difficult. 7-9 g: Unconsciousness without g-suit. 10+ g: Organ damage risk even briefly.

Negative G (Feet to Head)

-1 to -2 g: Uncomfortable, blood rushes to head. -2 to -3 g: Redout (vision turns red), severe discomfort. -3+ g: Dangerous, can cause hemorrhaging. Humans tolerate negative g much worse than positive g.

Forward/Backward G (Eyeballs In/Out)

10-15 g: Tolerable for seconds (crash forces). 20-25 g: Survivable briefly with restraints. 40+ g: Severe injury likely. 100+ g: Usually fatal. Direction matters—body tolerates horizontal forces better than vertical.