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Edexcel PHYSICS Doubts

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studz:

--- Quote from: Deadly_king on June 05, 2011, 10:43:21 pm ---This is because you made two readings before calculating the answer. I've not read the question but am pretty sure there was something like initial and final readings.

Since two readings were made, same uncertainty was carried out twice. That's why we multiply it by two ;)

Hope it helps :D

--- End quote ---

i dont get it where did we take two readings  ???
we just had a table of values for time in secs.

Nobody:

--- Quote from: Dangerous99 on June 05, 2011, 11:02:18 pm ---then shouldnt the uncertainty be 0.01 because the values they give are 18.66 and 18.46 they can only read it upto 0.01?
sorry by the way im just panicking here thats y im pressing on it so much

--- End quote ---

look, let's take random values from a meter rule
ALL in CENTIMETRE
56.7
43.6
34.6
1.7
09.7
99.9

now, have a look. 56 CM & 7 MM
so, the smallest value is "*.X"
so, that .X will be 0.1 and not any less.
you can't read "26.77" cm on a meter rule. that's impossible value to get.

Deadly_king:
In order to measure the time taken, we need to take two readings.

!st reading : 0.00
2nd reading : 3.02

So we got the same uncertainty twice ;)

Same applies for the other measurement ;)

Dangerous99:

--- Quote from: Nobody on June 05, 2011, 11:19:40 pm ---look, let's take random values from a meter rule
ALL in CENTIMETRE
56.7
43.6
34.6
1.7
09.7
99.9

now, have a look. 56 CM & 7 MM
so, the smallest value is "*.X"
so, that .X will be 0.1 and not any less.
you can't read "26.77" cm on a meter rule. that's impossible value to get.

--- End quote ---

I get what u mean. 0.1 is the uncertainty on the meter rule rite?
but the question I was doing they give the values 18.66 and 18.64 so obviously they can can only read it upto 0.01 sig figures, what will the uncertainty be in this case?

Nobody:

--- Quote from: Dangerous99 on June 05, 2011, 11:25:30 pm ---I get what u mean. 0.1 is the uncertainty on the meter rule rite?
but the question I was doing they give the values 18.66 and 18.64 so obviously they can can only read it upto 2 DECIMAL PLACES, what will the uncertainty be in this case?

--- End quote ---

yes!
yes! It will be 0.01.
boy, you're smart!  :D ;)

significant figures & decimal place are two different things ;)

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