Hi, in this session we will be learning more about clocks. I know you have been seeing clocks

everyday but you have never done some calculations on clocks. You will be doing it today. So what

really is a clock? It is a circular race between the hour hand and the minute hand. Don’t believe me,

have a look. The minute hand is the faster runner and the hour hand is the slower runner and they

are running in the same direction. Isn’t it a circular race? What really is the circumference of this

circular race? Well, circumference is given in two units, one is degrees, so the entire dial is nothing

but 360 degrees so that is one unit of circumference and the other unit is minute spaces. So what

really is a minute space, it is a one minute space on the circumference. Distance corresponding to

one minute, so it has totally 60 minute spaces, right, the full dial consists of 60 minute spaces. Now

for some calculations, if you look at the speed of the minute hand tell me in one hour the minute

hand covers how many degrees. In one hour the minute hand covers the full dial, so it covers 360

degrees. In terms of minute spaces, it covers the entire dial once again so it is 60 minute spaces in

one hour. On the other hand the hour hand covers only one twelfth of the dial in one hour. One

twelfth of 360 is nothing but 30 degrees or it is 5 minute spaces, if you know the hour hand covers

only 5 minute spaces in one hour. Let’s convert all of these units in per minute which means I would

divide each one of them by 60. So, the speed of the minute hand will be 6 degrees per minute or 1

minute spaces per minute. Likewise the speed of the hour hand would be, divide by 60, right, it is

half a degree per minute or 1 by 12 minute spaces per minute. Let’s now calculate their relative

speed, as you know they were travelling in the same direction, which means the relative speed will

be nothing but the difference. So the relative speed in terms of degrees will be 11 by 2 or 5 and a

half degrees per minute. Or in terms of minute spaces, it will be 11 by 12 minute spaces per minute.

Now you need to know these two values very well in order to solve questions on clocks. So just

remember them.

Well, some general facts about clocks. Okay, let’s fill in the blanks these values.

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