I think its cause of the weird answers in back of textbook that are confusing me. I made a lot of grammar errors lol cause i was in a rush sorry about that.
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1. Carbon nanotube is 30 nm in metre it is 3 x 10^-8 m why not 3.0 x 10^-8 m?
2. 20 ms to second = 2 x 10^-3 second why not 2.0x 10^-3 second
3. 280 mm+ 37 cm (look at value that has least estimated value)…so when u convert 280 mm it becomes 280 x 10^-1 cm+ 37 cm (7 lowest estimated) value so answer is 65 what if you do it the other way 37 cm is 37 x 10^2 mm+ 280 mm the 7 on 37 is estimated so answer should be 65 x 10 mm?? Am i doing this wrong I’m just trying to keep the answer with least estimated value.
4. 470 +5.89898=476 cause 0 is estimated..?
5. Speed of 100 km/h to miles per hour… the answer has 3 sig digs in the book but I thought 100 could have 1- 3 sig digs.
6. Masses between a proton and neutron 1.674927 x 10 ^-27 – 1.672621 x 10^-27= answer will have 7 sig digs right. But how come in answer in back it is 2.306 x 10^-30? Not 2.306000 x 10^-30.
7. Do sig digs matter in constant values.. Earth to sun constant value is 1.495 988 x 10^11 and earth to moon = 3.844 x 10^8 so farthest distance from sun to moon (when u add them can be ) 1.499 832 x 10^11( answer in back of book)….. but 3.844 has 3 decimal places so shouldn’t the answer be 1.500 x 10^11.
8. Speed of light is 3.00 x 10^8 m/s so when finding how long it takes for light to go from sun to earth the answer should have 3 significant digits like the speed of light?( therefore constants like speed of light specific heat of water, mass of neutron etc are considered in when determining number of sig digs to state, but unit conversions used in calculations are not used to determining number of sig digs in a calculation.
9. 460.299+ 390.0008+6.123 +5.07 final answer should have 5 sig digs but why does answer key say 6.
10. A apartment is 30 storeys high show height in meter the metres value should have 2 sig digs>?
11. 2.2 x 10^8 years ….in seconds is 6.937…x10^15 seconds but in answer key the answer is 7.0 x 10^15… But the number that is being dropped is 3 so shouldn’t the answer be 6.9 x 10^5 seconds.
12. Certain moth consumes 80,000 times its own weight…this would be included in determining sig digs because it is a measurement not counted value? How much would a human weighting 3.0 kg have to eat to compete so 3.0 x 80,000= answers should have 2 sig digs cause of 3.0? say a human weight 900000000 kg than the answer should only have 5 sig digs cause of 80,0000
13. At one time Fermi said his 50 min lecture lasted one micro century how close was his estimate .. This kind of question is confusing how many sig digs should answer have one? I get an answer of 2.56mins or 153.6 seconds off.
14. Canada speed limit is 100 km/h ( to m/s answer is 27.8 m/s) again this is confusing because does 100 have one sig dig 2 or 3
15. A mean solar day increases by 1 ms per century how much longer would a day be in 30000 years…the answer should have one sig dig cause of 1? So I get 3 x 10 ms but answer in back says 30 ms….
16. How long will it take from now for the day to be a minute longer because rate is 1 ms per century …answer is 6 x 10^6 years right?
Sooooo….. The only things not included in determining sig digs are things that are physically counted and unit conversions.