Hi, in this session we will be doing the concept of Proportionality of Speed and also Average
Speed. What really is speed, well, a vehicle which covers a certain distance in certain
amount of time, well, it would have covered this distance in some time, it would have
travelled in some speed. So speed is nothing but distance upon time. As you would have
seen from the formation, speed and distance would be directly proportionate, which means
at a higher speed you are expected to cover longer distance in the same amount of time,
right. On the other hand, speed and time as you can see are inversely proportionate, which
means to cover the same distance you will take less time at a higher speed. Well, that is the
proportionality of speed, time and distance. What that means is, if the speed changes in the
ratio a is to b, then the time taken to cover the same distance, since time and speed are
inversely proportionate, time taken would be in the ratio b is to a, while the distance
covered in the same amount of time, remember distance and speed were directly
proportionate, so distance covered would be in the same ratio which is a is to b.
Let us now look at some of the conversions.
How do you convert speeds from meter per second to kilo meters per hour. So one kilo
meter per hour is nothing but 5 by 18 meters per second. Which means if I have to convert
any value of speed from kilometre per hour to meters per second, I multiple 5 by 18. One
meter per second on the other hand would be 18 by 5 kilo meter per hour. It is the reverse,
Any idea what is 1 mile, well 1 mile is 1.6 kilo meters so 1 mile per hour would be nothing
but 1.6 kilo meter per hour. Now that is as far as the proportionality of Speed, Time and
Distance is concerned.
Let’s look at the next topic which is Concept of Average Speed. Now when do we use this
concept of average speed. When a vehicle is covering different speeds for different amount
of time or different distances at different speeds, for example, when different parts of the
journey is covered at different speeds, concept of Average Speed comes into play. So let’s
look into this particular train.