Unit Conversion & Significant Figures: Crash Course Chemistry #2
A unit is the frequently arbitrary designation we have given to something to convey a definite magnitude of a physical quantity and every quantity can be expressed in terms of the seven base...
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2640 lumens. 1 foot. 2.3 kilograms. 9 volts. Aaah! I just closed the circuit with my tongue and I felt all 9 of the volts. So what do all these things have in common? They're units. Yes, but they're also absolutely, completely arbitrary. [Theme Music] You know who decides how much a kilogram weighs? A hunk of platinum and iridium known as the International Prototype Kilogram or IPK. The IPK isn't just how much a kilogram weighs. In a very real sense the IPK is the kilogram. Every other kilogram is exactly the same as the IPK, and the IPK is the lump of metal that decides what that mass is. A kilogram is defined as being the same mass as the IPK. We made kilograms up just like we made up seconds and weeks and volts and newtons. There's not...
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2640 lumens. 1 foot. 2.3 kilograms. 9 volts. Aaah! I just closed the circuit with my tongue and I felt all 9 of the volts. So what do all these things have in common? They're units. Yes, but they're also absolutely, completely arbitrary. [Theme Music] You know who decides how much a kilogram weighs? A hunk of platinum and iridium known as the International Prototype Kilogram or IPK. The IPK isn't just how much a kilogram weighs. In a very real sense the IPK is the kilogram. Every other kilogram is exactly the same as the IPK, and the IPK is the lump of metal that decides what that mass is. A kilogram is defined as being the same mass as the IPK. We made kilograms up just like we made up seconds and weeks and volts and newtons. There's not...
