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Momentum and impulse question

I have got different answers to the book in questions 3 and 4, and I don't see where the mistake is (might be a mistake in the book)

Here is the question

ImageUploadedByStudent Room1493448819.502399.jpg

Here is my attempt. I have corrected the answers to that of the textbook in blue

ImageUploadedByStudent Room1493448871.164676.jpg


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Original post by Kyx
I have got different answers to the book in questions 3 and 4, and I don't see where the mistake is (might be a mistake in the book)

Here is the question

ImageUploadedByStudent Room1493448819.502399.jpg

Here is my attempt. I have corrected the answers to that of the textbook in blue

ImageUploadedByStudent Room1493448871.164676.jpg


Posted from TSR Mobile


It would be better that you upload a better quality pic of the question.

For question 3, it seems that you have used 22 ns instead of the the question stated duration 0.22 ns. It may be better that you state what are the book's answers.
I cannot figure out what question 4 is asking as the pic quality is not that clear.
Reply 2
Original post by Eimmanuel
It would be better that you upload a better quality pic of the question.

For question 3, it seems that you have used 22 ns instead of the the question stated duration 0.22 ns. It may be better that you state what are the book's answers.
I cannot figure out what question 4 is asking as the pic quality is not that clear.


Of course, that seems to be exactly what the problem is. Thx :smile:

Here's question 4:

ImageUploadedByStudent Room1493456977.947702.jpg


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idk what i'm doing wrong but i keep getting the change in momentum as -4.2*10^-22kgm/s.
change in momentum=mv-mu
((5x10^-25)x-420)-((5x10^-25)x420)= -4.2x10^-22kgm/s


Force=change in momentum/time
-4.2x10^-22/0.22x10^-9
F=1.9x10^12N
Reply 4
Original post by assassinbunny123
idk what i'm doing wrong but i keep getting the change in momentum as -4.2*10^-22kgm/s.
change in momentum=mv-mu
((5x10^-25)x-420)-((5x10^-25)x420)= -4.2x10^-22kgm/s


Force=change in momentum/time
-4.2x10^-22/0.22x10^-9
F=1.9x10^12N


You used 5*10^(-25) instead of 5*10^(-26)

:smile:


Posted from TSR Mobile
Original post by Kyx
Of course, that seems to be exactly what the problem is. Thx :smile:

Here's question 4:

ImageUploadedByStudent Room1493456977.947702.jpg


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As for question 4, double check your calculation on the trigo calculation,
a = 420* cos(60 deg) = 210.

And the duration should be 0.22 ns as stated in my previous post.
Reply 6
Original post by Eimmanuel
As for question 4, double check your calculation on the trigo calculation,
a = 420* cos(60 deg) = 210.

And the duration should be 0.22 ns as stated in my previous post.


Yes, of course. For some reason my calculator was in 'grad' mode, which I've never used :s-smilie:

Must have accidentally pressed that button :redface:

I get 210 now :smile:


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whops :biggrin:. It looked like 25 from the picture....
so for question 4 it seems like you made a mistake in calculations part ----> 420x(cosx60)=210
Reply 8
Original post by assassinbunny123
whops :biggrin:. It looked like 25 from the picture....
so for question 4 it seems like you made a mistake in calculations part ----> 420x(cosx60)=210


Yes, calculator was in the wrong mode :redface:


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