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Physics: Post your doubts here!

P1O2I3U4

P1O2I3U4

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Hassan Ali Abid said:
using the same formula first calculate the number of moles of gas filled in each balloon ...ryt ...
then ____ moles of gas : 1 ballons (number of balloons)
_______moles calculated in part b(1):x and by this calculate the total number of balloons.

calculate like this and see if the ans is ryt or not.
Click to expand...
Yes, I already tried that but I am getting 746 whereas the answer is 740.
 
Hassan Ali Abid

Hassan Ali Abid

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P1O2I3U4 said:
Yes, I already tried that but I am getting 746 whereas the answer is 740.
Click to expand...

the ans in ms is round off to 3sf...so ur ans much be less then 745 then when it will be roundoff to 3sf it will get to 740. You must have made some mistake in a calculation ....try to use the accurate values and then find the final ans ...see if it gets to 740 or not .
 
P1O2I3U4

P1O2I3U4

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Hassan Ali Abid said:
the ans in ms is round off to 3sf...so ur ans much be less then 745 then when it will be roundoff to 3sf it will get to 740. You must have made some mistake in a calculation ....try to use the accurate values and then find the final ans ...see if it gets to 740 or not .
Click to expand...
Unfortunately I am still not getting the answer. Have you tried to solve it yourself? Please try and see.
 
P1O2I3U4

P1O2I3U4

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Hassan Ali Abid said:
the ans in ms is round off to 3sf...so ur ans much be less then 745 then when it will be roundoff to 3sf it will get to 740. You must have made some mistake in a calculation ....try to use the accurate values and then find the final ans ...see if it gets to 740 or not .
Click to expand...
I am actually getting 746.6
 
snowbrood

snowbrood

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P1O2I3U4 said:
Have you seen the procedure in the mark scheme? I don't understand a word!
Click to expand...
Hassan Ali Abid said:
using the same formula first calculate the number of moles of gas filled in each balloon ...ryt ...
then ____ moles of gas : 1 ballons (number of balloons)
_______moles calculated in part b(1):x and by this calculate the total number of balloons.

calculate like this and see if the ans is ryt or not.
Click to expand...
find the number of moles of hydrogen that one balloon contains using the equation PV=nRT u will get n=0.56
one balloon 0.56moles
x no of balloons 415moles
calculate x u will get 741
 
usama321

usama321

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mm89mm said:
salams,
so i've got 2 questions that need checking.
I will provide everything, you just need to read.

1st question
It's about forces
View attachment 36895

The answer
View attachment 36897

And the other question and answer.

View attachment 36898

Thanks in advance.
Click to expand...


For the first question, there is no work done in moving an object horizontally in air, so the work done is only against gravity, that is while moving the object vertically... so F* vertichal heigh = 20 kJ

For the second question, you have to keep in mind that velocity is a vector. Thus when it bounces of, it is in the opposite direction and the velocity you will use in your calculation will be -12.2... so

1/2 *.2 * (15.8^2 - (-12.2) ^2)
 
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