in this video i'm going to talk about sr unit and si prefix sr unit is an international unit for the quantity and it's made up based on the seven major quantity that you can see it in this table the sr unit for length is meter and the symbol for meter is lowercase m the second quantity for si unit is mass the unit for mass in si system is kilogram and the symbol is lowercase k the third one is time and the sr unit for time is second and lowercase s is the symbol for time si unit for temperature is kelvin and the symbol for kelvin is k uppercase the amount of substance that is very important in chemistry has mole unit and the symbol is almost same but it doesn't have e at the end after the last two quantity for s i is mostly belong to the physics but i'm going to explain also these two here electric currents the unit is ampere and the symbol is a and luminous intensity the unit is candela and the symbol is cd all other units in physics chemistry and other science major is built on based on these seven units for example if you want to calculate area for an s square or for a rectangle we are going to multiply x times y or x times x so we should multiply these two lengths here so if we want to calculate the sr units for the area we should have length time length the unit for length is meter so meter times meter is equals to meter square so the sr unit for area is meter square for volume we have length time length time length so the sr unit for volume is m times m times m so is meter cube so let's have more example for the other quantity like speed or velocity we know the definition for speed or velocity is distance over time the unit for distance is meter and the unit for time is second so sr unit for speed or velocity is meteor per second for acceleration you know the definition of acceleration is change of a speed per time we already know a unit for change of speed it should be the same with the unit of speed so it's meter per second then the unit for time again is second so this one is equals to media per second a square from the second law of neotone we know force is equals to mass time acceleration so sr unit for mass is kilogram and for acceleration is meter per second square so sr unit for force is equals to km a second square when we have a unit on denominator we can convert it to the negative power and bring it to the denominator so instead of writing km over s square we can write it in this form also so this negative power it means this is belong to the denominator just to make it easier we can write it in this form also so the unit for all other quantity can be derived from these seven major units in chemistry and also in physics sometimes we have a very big or very small numbers and we need to convert these numbers to the scientific notation if you don't know how we can convert the numbers to scientific notation you can watch my video about the scientific notation the link is on the description of this video so let's say we have this number after converting to the scientific notation or we have some number like this to make it easier instead of using this power of 10 we are able to use some prefix in the international system or si i'm going to list some of these prefix in this table the power for giga is positive 9 and the symbol is g another prefix is mega the power for mega is positive 6 and the symbol is m kilo positive 3 k 70 negative 2 lowercase c milli negative 3 m as you can see here for mega and milli both of them is m so it's very important to know is it upper case or lower case micro negative six and symbol for micro is a gimmick ladder we call it mu nano negative 9 lowercase n and pico negative 12 and p so let's have some example for application of this prefix the negative theory power is belong to the milli so instead of 10 to negative 3 i just simply put it cinder so i can write 1.2 milligram for next example we have 10 to negative 9 and we can see here 10 to negative 9 is means nano so i can just write 5.22 instead of 10 to negative 9 i'm going to put its symbol and and then the unit for this so then 5.22 nano meter here is another example 8.9 times 10 to positive 9 hertz then 10 to positive 9 it means giga so i can just write the symbol for giga here then is going to be 8.9 giga hertz thank you for watching this video for watching more video please subscribe our youtube channel