What is the average speed of a bus that travels 170 km in 2 hours and then slows down to 70 km/hr?

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User Guide

Calculate average speed of a moving object from the total distance travelled and the time taken from start to finish.

Once you have entered a distance and a time period the average speed will appear in the answer box and two conversion scale will also show a range of values for distance versus speed and time versus speed.

Formula

This tool calculates average speed using the following formula:

v = d / t

Symbols

• v = Speed
• d = Distance
• t = Time

Distance Travelled

Enter the actual distance that is travelled by a moving object in any unit of distance measurement.

Time Taken

Enter the time taken to complete the distance travelled in any measurement unit of time.

Average Speed

This is the speed that a moving object would need to maintain without variation, in order to complete the distance travelled in the same period of time.

Applications

Examples of types of average speed calculations:

• Convert a journey distance in kilometres and the time taken in hours, to an average speed in mph.
• Determine the average speed of a runner in mph, from a track run distance in metres, and the stopwatch time in minutes or seconds.
• Calculate a training speed to complete a cycling route within a target period of time.

Related Pages
Rate, Time, Distance
Solving Speed, Time, Distance Problems Using Algebra
More Algebra Lessons

There are three main types of average problems commonly encountered in school algebra:
Average (Arithmetic Mean)
Weighted Average and
Average Speed.

The following diagram shows the formula for average speed. Scroll down the page for more examples and solutions on calculating the average speed.

Example:
John drove for 3 hours at a rate of 50 miles per hour and for 2 hours at 60 miles per hour. What was his average speed for the whole journey?

Solution:
Step 1: The formula for distance is

Distance = Rate × Time
Total distance = 50 × 3 + 60 × 2 = 270

Step 2: Total time = 3 + 2 = 5

Step 3: Using the formula:

Answer: The average speed is 54 miles per hour.

Be careful! You will get the wrong answer if you add the two speeds and divide the answer by two.

How To Solve The Average Speed Problem?

How to calculate the average speed?

Example:
The speed paradox: If I drive from Oxford to Cambridge at 40 miles per hour and then from Cambridge to Oxford at 60 miles per hour, what is my average speed for the whole journey?

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How To Find The Average Speed For A Round Trip?

Example:
On Alberto’s drive to his aunt’s house, the traffic was light, and he drove the 45-mile trip in one hour. However, the return trip took his two hours. What was his average trip for the round trip?

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How To Find The Average Speed Of An Airplane With Good And Bad Weather?

Example:
Mae took a non-stop flight to visit her grandmother. The 750-mile trip took three hours and 45 minutes. Because of the bad weather, the return trip took four hours and 45 minutes. What was her average speed for the round trip?

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How To Relate Speed To Distance And Time?

If you are traveling in a car that travels 80km along a road in one hour, we say that you are traveling at an average of 80kn/h.

Average speed is the total distance divided by the total time for the trip. Therefore, speed is distance divided by time.

Instantaneous speed is the speed at which an object is traveling at any particular instant.

If the instantaneous speed of a car remains the same over a period of time, then we say that the car is traveling with constant speed.

The average speed of an object is the same as its instantaneous speed if that object is traveling at a constant speed.

• Show Video Lesson

How To Calculate Average Speed In Word Problems?

Example:
Keri rollerblades to school, a total distance of 4.5km. She has to slow down twice to cross busy streets, but overall the journey takes her 0.65h. What is Keri’s average speed during the trip?

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How To Use Average Speed To Calculate The Distance Traveled?

Example:
Elle drives 169 miles from Sheffield to London. Her average speed is 65 mph. She leaves Sheffield at 6:30 a.m. Does she arrive in London by 9:00 a.m.?

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How To Use Average Speed To Calculate The Time Taken?

Example:
Marie Ann is trying to predict the time required to ride her bike to the nearby beach. She knows that the distance is 45 km and, from other trips, that she can usually average about 20 km/h. Predict how long the trip will take.

• Show Video Lesson

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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Use this speed calculator to easily calculate the average speed of a vehicle: car, bus, train, bike, motorcycle, plane etc. with a given distance and travel time. Returns miles per hour, km per hour, meters per second, etc.

    Quick navigation:

The average speed calculation is simple: given the distance travelled and the time it took to cover that distance, you can calculate your speed using this formula:

Speed = Distance / Time

The metric unit of the result will depend on the units you put in. For example, if you measured distance in meters and time in seconds, your output from the average speed calculator would be ft/s. If distance was measured in miles and time in hours, then output will be in miles per hour (mph, mi/h), and so on for km/h, m/s, etc. - all supported by our tool.

    How to calculate the average speed of a car?

Let us say that you travelled a certain distance with your car and want to calculate its average speed. The easiest way to do that would be by using the speed calculator above, but if you prefer, you can also do the math yourself. Either way, one needs to know the distance. If you have noted the distance on your odometer then you can use that number. Other options are to use a map (e.g. Google Maps) and measure the distance travelled based on your actual path (not via a straight line, unless you travelled by air in which case that would be a good approximation), or to use a GPS reading if you used navigation during the whole trip. Then you need to know the travel time. Make sure to subtract any rests or stops made from the total trip duration.

For example, if the total distance travelled was 250 miles and the time it took was 5 hours, then the average speed was 250 / 5 = 50 miles per hour (mph). If the distance was 200 kilometers and it took 4 hours to cover it, then the speed was 200 / 4 = 50 km/h (kilometers per hour).

    Finding average speed examples

Example 1: Using the equation above, find the speed of a train which travelled 120 miles in 2 hours and 10 minutes while making four stops, each lasting approximately 2.5 minutes. First, subtract the time spent at the train stops: 2.5 x 4 = 10 minutes. 2:10 minus 10 minutes leaves 2 hours of travel time. Then, apply the avg speed formula to get 120 miles / 2 hours = 60 mph (miles per hour).

Example 2: A cyclist travels to and from work, covering 10 km each way. It took him 25 minutes on the way to work and 35 minutes on the way back. What is the cyclist's average speed? First, add up the time to get 1 hour total. Also add up the distance: 5 + 5 = 10 kilometers. Finally, replace in the formula to get 10 / 1 = 10 km/h (kilometers per hour) on average in total.

Average speed (what this calculator computes) and average velocity are not necessarily the same thing though they may coincide in certain scenarios. This is basic physics, but a lot of people find it confusing. Here are the differences in short.

Speed is a scalar value whereas velocity is the magnitude of a vector. Speed does not indicate direction whereas velocity does. The two coincide only when the journey from the start point to the end point happens on a straight line, such as in a drag race. If the movement path is not a straight line then the average velocity will be smaller than the mean speed.