Hello friends this video on motion and time pad food is brought to you by exam for calm no more fear from exam now when we talk about motion another important we are actually talking about movements or we are talking about position changes so when it comes to move friends something which is very commonly being used in our day-to-day life is fast and .
Slow so how do we know which object is moving fast and which object is moving slow so how exactly do we define that or how exactly do we determine that what determines the speed of motion so that is where we introduce speed so we will talk about speed a little later but in this picture what do you see you observe that the blue car was fast and the red .
Car was slow so why was this an example of fast motion because it very quickly changed its position so in a short interval of time it reached from position a to position B but time but the red car it took more time to reach from position a to position B so basically how much time it takes by a particular object to cover a particular .
Distance will define whether that object is undergoing fast motion or slow motion so that as well comes the concept of fast and slow so let's look at it and how do we determine that which is faster the distance moved by objects in a given interval of time decides which one is faster or slower so let's look at this example so you have a bike and you have .
A bycicle so these are the two vehicles that you have so now if you want to compare which of these two is faster so let us try to compare these two vehicles now let's say that we fix a time interval so let's say we we fix a time interval of five minutes and then we just observe how much distance is covered by this bike and how much .
Distance is covered by this bike now what we see is that in five minutes this bike could cover a distance of around let just we'll just take examples let's say it covered a distance of three kilometers and in the same duration of five minutes this bicycle could cover a distance of two kilometers okay so which one is fasted now the time interval is .
The same so in the same time the bike covered more distance when compared to the cycle so that means the bike is faster so the bike is traveling fast that is why it would cover more distance in the same time when compared to the bicycle so this is how we can determine which one is faster so the fast or slow is actually defined by the rate of .
Change of position with time that is how fast the position is changing with time because when we were talking about motion we they're only talking about the change in position with time but when we talk about the fast or slow of a fast or slow speed of a vehicle we are actually talking about the rate at which the position is changing with time how fast .
Or how slow the position changes with time so that is how we can say that the bike is faster and the bicycle is slower so this is where we introduce the term speed so when we talk about fastness or slowness of motion we have to introduce speed so water speed it is the rate at which an object covers distance that means how fast or how slow how quickly .
Or how slowly an object is able to cover distance with time so speed is a scalar quantity what is a scalar quantity it is such a quantity which only needs magnitude for its definition that is just a value so we say the speed of a vehicle is 5 meter per second so that's the speed so we do not need any direction since these type of quantities .
Are called scalar quantities you will learn more about scalar and quantities in your higher classes so let's look at an example to understand speed even better so as I said speed is nothing but the distance covered divided by the time taken so this is how we calculate speed of an object so let us take the example of the sky so if we say .
That this car travels 50 kilometers in one hour so let us say that it travels 50 kilometers in one hour so what would be the speed of the car so the speed of the car is actually distance traveled which is 15 kilometer divided by time taken which is one hour so basically the speed of the car would be 50 kilometers per hour so that is how we define speed .
Now any object which has a higher speed moves faster because it is traveling more distance over a specific period of time any object which has a lesser value of speed is traveling at a slower speed so it has a slow motion so that that's about speed so let us look at more examples of speed so let's look at this example where this little boy is trying .
To travel from his home to the McDonald's so that's the coils on the bicycle so now this little boy is moving or he is traveling from his home to the McDonald's and this his travel time is 10 minutes so it takes in 10 minutes to go from his house to the McDonald's and the distance between his house and the McDonald's is 2 kilometres McDonald's is .
2 kilometers away from his house so if I asked you to calculate the speed with which the boy is moving how will you do that so the speed is nothing but the distance which he traveled which is nothing but 2 kilometers divided by the time she took that is nothing but ten minutes so if you convert minutes to seconds so .
It is going to be 10 by 60 hour so this is going to be 12 kilometers per hour so this is the speed with which the boy was moving when you traveled from his home to the McDonald's so this defines that means it now what does this 12 kilometer per hour means now literally it means that the boy traveled in one hour 12 kilometers but actually he traveled only .
2 kilometers but speed tells us that ok this is the rate at which he moved so had he traveled one had he traveled for 1 hour he could have covered 12 kilometers so it just gives you the rail it just gives you the distance which the person could have covered in one hour or in one second or in one minute so with respect to whatever unit of time you are .
Referring to so that is how we calculate speed now similarly let's say that the ball also comes back from the McDonald's so let's say we take another example where the boy goes to the McDonald's like he travels from his house to the McDonald's and then immediately he comes back from McDonald's to his house and we say that the what would be the total .
Distance now let's say the total distance of going and coming back would be 4 kilometers correct and let's say that the total time that he took was say 30 minutes now we are assuming that he can't get down at McDonald's at all he just went there but as soon as he reached reached McDonald's he changed his mind and he started coming back to .
Home so if we say that at the time he took was 30 minutes in that case what would be the overall speed so again you can calculate it in a similar way distance traveled by time taken so I am leaving that as an exercise to you so I hope it is clear that how do we calculate speed and water speed all about what the speed tell us it just .
Tell us distance that a particular object can cover in unit time whether it is in one hour or one second or in one minute thank you please visit www.hp.com/recycle subscribe to our YouTube channel for latest updates thank you once again