Speed Converter
Convert between mph, km/h, m/s, knots, and other speed units
Common Speed Conversions
Speed in Real Life
Walking Speed
≈ 5 km/h (3.1 mph, 1.4 m/s)
Highway Speed
≈ 120 km/h (75 mph, 33 m/s)
Commercial Jet
≈ 900 km/h (560 mph, 250 m/s)
Cheetah
≈ 110 km/h (68 mph, 31 m/s)
About Speed Measurement
Speed measurement is fundamental to understanding motion, transportation, and the physical world around us. From the velocity of subatomic particles to the speed of galaxies, measuring speed accurately is crucial in physics, engineering, sports, and everyday life.
What is Speed?
Speed is a scalar quantity that measures how fast an object moves, defined as the rate of change of distance with respect to time. Unlike velocity, speed has magnitude only and no direction. The fundamental formula for speed is:
Speed = Distance ÷ Time
v = d/t
Common Speed Units and Conversions
Speed can be measured in various units depending on the application and region. Here are the most commonly used speed units with their conversion factors:
| Unit | Symbol | Conversion to m/s | Common Use |
|---|---|---|---|
| Meters per second | m/s | 1.000 | SI unit, physics |
| Kilometers per hour | km/h | 0.2778 | Road vehicles, most countries |
| Miles per hour | mph | 0.4470 | US, UK road vehicles |
| Knots | kn | 0.5144 | Aviation, maritime |
| Feet per second | ft/s | 0.3048 | Engineering, ballistics |
| Mach number | M | 343 × M | Supersonic aircraft |
Speed vs Velocity: Key Differences
While often used interchangeably in everyday language, speed and velocity have distinct meanings in physics:
Speed (Scalar)
- • Magnitude only (how fast)
- • Always positive
- • Formula: v = d/t
- • Units: m/s, km/h, mph
- • Example: "60 km/h"
Velocity (Vector)
- • Magnitude + direction
- • Can be positive or negative
- • Formula: v⃗ = d⃗/t
- • Units: m/s, km/h, mph
- • Example: "60 km/h north"
Speed Measurement Tools and Instruments
Various instruments and technologies are used to measure speed accurately in different applications:
Automotive Speedometers
- • Mechanical: Cable-driven from transmission
- • Electronic: Hall effect sensors
- • GPS-based: Satellite positioning
- • Accuracy: ±2-5% typical
Scientific Instruments
- • Radar guns: Doppler effect
- • Laser velocimeters: Light scattering
- • Pitot tubes: Air pressure differential
- • Accelerometers: Integration method
Speed in Real-World Applications
Speed measurement is critical across numerous industries and applications:
| Application | Typical Speed Range | Measurement Method | Importance |
|---|---|---|---|
| Highway Traffic | 20-130 km/h | Radar, cameras | Safety, law enforcement |
| Commercial Aviation | 800-950 km/h | Pitot tube, GPS | Navigation, fuel efficiency |
| Wind Speed | 0-300 km/h | Anemometer | Weather forecasting |
| Manufacturing | 0.1-1000 m/min | Encoders, tachometers | Quality control |
| Sports Performance | 5-45 m/s | High-speed cameras | Training optimization |
Speed Calculation Examples
Understanding speed calculations through practical examples:
Example 1: Average Speed
A car travels 150 kilometers in 2 hours. What is the average speed?
Speed = Distance ÷ Time = 150 km ÷ 2 h = 75 km/h
Example 2: Unit Conversion
Convert 60 mph to m/s
60 mph × 0.4470 = 26.82 m/s
Example 3: Relative Speed
Two cars approach each other at 80 km/h and 60 km/h. What is their relative speed?
Relative speed = 80 km/h + 60 km/h = 140 km/h
Speed Measurement Standards and Calibration
Accurate speed measurement requires proper calibration and adherence to international standards:
International Standards
- • SI base unit: meter per second (m/s)
- • NIST traceability for US measurements
- • ISO 17025 for calibration laboratories
- • ASTM standards for specific applications
Calibration Methods
- • Reference speedometers
- • Calibrated rollers and dynamometers
- • GPS-based verification systems
- • Laser interferometry for high precision
Why Speed Measurement Matters
Accurate speed measurement is crucial for safety, efficiency, and scientific advancement:
Safety
- • Traffic speed limits
- • Aircraft approach speeds
- • Industrial safety protocols
- • Emergency response timing
Efficiency
- • Fuel consumption optimization
- • Manufacturing process control
- • Transportation logistics
- • Energy conservation
Research
- • Physics experiments
- • Sports performance analysis
- • Weather pattern studies
- • Material testing
Key Speed Reference Points
Speed of Light: 299,792,458 m/s (ultimate speed limit)
Speed of Sound: 343 m/s in air at 20°C
Earth's Rotation: 1,674 km/h at equator
Walking Speed: 1.4 m/s (5 km/h)
Highway Speed: 33 m/s (120 km/h)
Commercial Jet: 250 m/s (900 km/h)
Frequently Asked Questions About Speed Conversion
Related Speed and Conversion Tools
Length Converter
Convert between meters, feet, inches, and more
Time Converter
Convert seconds, minutes, hours, and time units
Acceleration Converter
Convert acceleration units like m/s² and ft/s²
Flow Rate Converter
Convert flow rates and velocity measurements
Angular Velocity
Convert rotational speed and angular velocity
Fuel Consumption
Convert fuel efficiency and consumption rates