Speedometer facts for kids
A speedometer is a cool device in a vehicle that shows you how fast you are going. It's a type of gauge that measures your current speed. Most speedometers show speed in either miles per hour (mph) or Kilometres per hour (kph). Miles per hour are used in countries like the United States, while kilometres per hour are used in many other parts of the world.
Did you know that speedometers weren't always standard in cars? At first, they were an extra feature you could buy. But by about 1910, they became a regular part of every car.
Contents
How Speedometers Were Invented
The first electric speedometer was created by a Croatian inventor named Josip Belušić in 1888. He called his invention a "velocimeter." Before that, Charles Babbage, a famous inventor, also made an early type of speedometer. These were often used on locomotives, which are the engines that pull trains.
A German inventor, Otto Schulze, received a patent for his speedometer on October 7, 1902. His design used a spinning, flexible cable. This cable was usually connected to the vehicle's transmission, which helps control the power from the engine to the wheels. However, some older cars, like the first Volkswagen Beetle, and many motorcycles, got their speed information from a cable connected to a front wheel.
Why Speedometers Might Not Be Perfect
Most speedometers are very close to accurate, but they can have a small difference, usually about 10%. This is mostly because of small changes in the size of your tires. Things like how worn out your tires are, the temperature, the air pressure inside them, and how much weight your vehicle is carrying can all affect the tire's size.
Car makers usually set speedometers to show a slightly faster speed than you are actually going. This is a safety measure.
What Happens with Low Tire Pressure
When a tire doesn't have enough air, we say it's "underinflated." This can cause the tire to get too hot and also makes its overall size a little smaller. Because the tire is smaller, it has to spin faster to cover the same distance. This means your speedometer might show you are going 70 mph, but you could actually be traveling at 72 mph!
Images for kids
-
A modern speedometer in a Toyota Corolla.
-
A digital, LCD speedometer in a Honda Insight.
-
A speedometer showing mph and km/h along with an odometer and a separate "trip" odometer (both showing distance traveled in miles).
.jpg)
See also
In Spanish: Velocímetro para niños
