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Speed, distance and time in physics

In physics, understanding physics distance and time is important and knowing two of the three, you can actually calculate the value of the other. For example if we knew the distance and average speed, it would be easy to calculate the amount of time it takes an object to travel from point A to point B. The same is also true, for calculating speed and distance, you just have to know two of the values and using the formula bellow, you can get the other value.

 Average speed = ^distance/_Time

Average speed is usually measured in kilometers per hour (km/hr), miles per hour (mi/hr) and so forth.

Here is how that works, let us say that the unit of measurement for time is 1 hour, for distance is 1km. then using the formula above:

 Average speed = ^1km/_1hr

As you can see the unit of measurement for speed will then be ^km/_hr (also pronounced as kilometer per hour). If you were given the speed and time you would calculate the distance traveled as follows:

 distance = average speed x time 

 =>  ? = ^km/_hr x hr

 

 =>  ? = ^km/_hr x hr

 

 =>  ? = km   -- which is a unit of measurement for distance.

Practical distance, time and speed problem

Before we go on I have to stress the need to understand the units of measurement. Distance can measured in (cm (centimeters), mm (millimeters), inches, feet, m(meters), km (kilometers)). Time can be measured in seconds, minutes and hours. Thus speed can be measured in units of distance over the units of time.

For example: Kana throws a ball and it lands 25m away. It took the ball 15 seconds to land. At what average speed did Kana throw the ball?

Average speed = distance / time

          = 25m / 15s

          = 1.67m/_s

What this says is that it took the ball traveled the average 1.67meters for every second. This however does not tell you what the speed was at a particular time, what it tells you is the aggregate speed, in other words, you would not be able to tell how much slower or faster the ball was traveling towards the end. The only way you would know that is by plotting a distance time graph, that way if you timed when the object hit different points along the traveled distance, you could identify sections of faster and slower movements

Example 2: Makena ran a marathon at the speed of 10km/h and it took her 3 hours to finish the race. How far did she run?

solution:
distance = speed x time
= 10km/h x 3h
= 30km

Speed and Velocity
Speed is a measure of how fast something is going, usually measured in meters per second (m/s) or kilometers per hour (km/h). The relationship between distance, speed and time is discussed in detail in posting

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Speed, distance and time in physics

Practical distance, time and speed problem

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