01:160:161 Lecture 2: Chem lecture 2 notes
Document Summary
Original: 1/10,000,000 of distance between the north pole and the equator. Defined 1960: 1,650,763. 73 wavelengths of a particular orange-red line in krypton-86. Modern (since 1983): the distance traveled by light in 1/299,792,458 second. Second: the amount of time corresponding to 9,192,631,770 oscillators of a cesium atom. The mass of a particular platinum-iridium cylinder (international prototype kilogram) 10-12 pico p standard prefixes are used for every 3 powers of 10. This is used mostly for centimeter (cm)- a common unit of length and cm3, a common unit of volume. Liter=1000 cm3 or 1 cubic decimeter (dm3) m2, cm2 m3, cm3. Inertia is the resistance to change in motion (acceleration). The uncertainty depends on the measuring instrument used. We have no knowledge of any digit past the uncertain digit. Pre(cid:272)edi(cid:374)g zeroes (cid:894)zeros (cid:271)efore a(cid:374)y (cid:374)o(cid:374)zero digits(cid:895) are just pla(cid:272)e holders. Zeros at the end of a measurement are placeholders unless they follow a decimal point.
