Content

• To step
• Part 1 of 2: Learning the formula
• Part 2 of 2: Applying what you've learned

Maybe you are planning a trip by car and want to know how fast you need to drive to reach a certain destination on time. Or maybe you are curious and want to calculate the average speed of a train between two stations. Or maybe you need help doing your homework. Whatever your reason, it is always useful to know how to calculate average speed.

To step

Part 1 of 2: Learning the formula

1. Understand the definition of speed. Speed ​​can be defined as "the rate at which an object travels a distance". Speed ​​can only be expressed in a combination of distance and time measurements. To understand that, there are two other related terms that you need to understand as well.
   • Velocity vector (in physics) is very similar to velocity, but there is an important difference. A correct description of the velocity vector must include the direction in which the object is moving. Therefore, the velocity vector is calculated with a slightly different formula. The velocity vector, unlike velocity, can also be expressed as a negative number. For example, an object thrown up can have a positive velocity vector when it goes up and a negative velocity vector when it comes down again. As a result, the formulas for speed and velocity vector differ from each other.
   • Acceleration is the rate at which the speed of an object gets bigger. It is expressed as a unit of distance (meters, kilometers, etc.) divided by a unit of time (usually seconds) squared. One of the most common numbers used in physics is 9.8 m / s (2). That number stands for the gravitational acceleration: the acceleration at the earth's surface as a result of gravity.
2. Learn the difference between average and instantaneous speed. Instantaneous speed is the speed at which an object is moving at a certain point in time. In a car, your speedometer indicates instantaneous speed - the speed at which you are moving at that specific moment. But your speed at one point in time has no direct influence on the average speed. If you move very fast for one second, but then go much slower, then that short high speed has little influence on the total travel time. Average speed refers to your speed between two specific points. It is directly related to the time it took to get from the first point to the second point.
3. Get to know the formula. The terms used to describe speed come in handy to explain the formula used to calculate it. Speed ​​of cars, for example, are expressed in kilometers per hour (km / h). The term "per" is used to indicate a division. "Divisions" are expressed in fractions. Think of 50 kilometers per hour as a fraction: 50 kilometers / 1 hour. The terms most commonly used to indicate speed use divisors (units of time in this case) in the first power. From here you can already guess the formula: speed = distance / time.

Part 2 of 2: Applying what you've learned

1. Measure the distance traveled. As explained earlier, you can only determine average speed if you know the distance an object has traveled.
   • In practical applications such as driving, you can use tools on the internet to calculate the actual distance you have driven. Google Maps (maps.google.com), Mapquest (mapquest.com), and Michelin (viamichelin.com) all provide route information, including total distance.
2. Determine the time it takes to travel the distance. The physical formula for speed is normally written as d/Δt, at which d the distance is and t the time. The Δ symbol (the classical Greek letter delta) gives change On. You have to determine the change in time from start point to end point. If you are keeping time using a clock, you will need to subtract the start time from the end time. (This is easiest if you use the 24-hour time format.)
   • If you started driving at 8:00 am and finished at 1:00 pm, you subtract 8:00 from 1:00 pm. So the journey took 5 hours.
3. Divide the distance by time. It goes without saying that the units used to express distance and time are separate, so they cannot disappear by division. Each result remains a ratio of distance related to time.
   • As an example, let's say you drove 150 kilometers in 3 hours. To calculate the average speed, divide 150 kilometers by 3 hours. The result is 50 kilometers per hour (150km / 3h = 50km / h).