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Impulse/Momentum?/Physics/Mechanics help please! watch

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    *PIC BELOW*

    Q1 is for 6 marks, I did Ft=mv-mu then got v to be 11.5m/s. Is this correct?

    Q2 is for 8 marks. I did the exact same method and got v = 49.3m/s.

    This doesn't make sense? How do I solve these questions

    Thanks
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    thanks again!
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    Hey, I'm a current Phyiscs/Maths A2 student- I had a go at both of the questions and I've attached a picture of my workings.

    Name:  image.jpg
Views: 68
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    In the first question, I'm sure we both got the same thing so I'm certain it's right. I'm not sure why you would use the impulse equation to solve it because the object isn't colliding with anything- and you learn f=ma and suvat in both physics and m1 maths, so you should be familiar with both. Still, you got the right answer so well done ^_^

    The second question I was a bit confused with (and we got different answers), so maybe we can help eachother on that. The main assumption I made was that the impulse of both objects would be the same, but I'm not entirely sure that's true. And if it is, my working seems very short for 8 marks. Let me know what you think about my method!!
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    Small update: I did a quick googl and I found a solution- your answer for Q2 is right!! It looks like my mistake was the double negative. A bit confused about why that's not positive though, since the direction changes, do you have any wisdom on that??
    Name:  image.png
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    (http://www.jiskha.com/display.cgi?id=1476954557)

    Thanks yo!
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    (Original post by sabruh)
    Hey, I'm a current Phyiscs/Maths A2 student- I had a go at both of the questions and I've attached a picture of my workings.

    Name:  image.jpg
Views: 68
Size:  491.2 KB

    In the first question, I'm sure we both got the same thing so I'm certain it's right. I'm not sure why you would use the impulse equation to solve it because the object isn't colliding with anything- and you learn f=ma and suvat in both physics and m1 maths, so you should be familiar with both. Still, you got the right answer so well done ^_^

    The second question I was a bit confused with (and we got different answers), so maybe we can help eachother on that. The main assumption I made was that the impulse of both objects would be the same, but I'm not entirely sure that's true. And if it is, my working seems very short for 8 marks. Let me know what you think about my method!!
    I do think yours is correct as I forgot to include the extra minus sign, so well done!
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    (Original post by zezno)
    I do think yours is correct as I forgot to include the extra minus sign, so well done!
    Funnily enough, I posted another post which is currently under review. I googled the question and I found an answer the same as yours. So I don't know if I'm right or not. Here's a pic:

    Name:  image.png
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    (Original post by sabruh)
    Funnily enough, I posted another post which is currently under review. I googled the question and I found an answer the same as yours. So I don't know if I'm right or not. Here's a pic:

    Name:  image.png
Views: 60
Size:  101.1 KB

    loool omg I'm so confused.
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    Both of the answers so far look wrong to me.

    The screenshot ones have the impulse in the same direction as the initial velocity.

    The calculations do some magic with 1.5 that isn't legal!
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    (Original post by RogerOxon)
    Both of the answers so far look wrong to me.

    The screenshot ones have the impulse in the same direction as the initial velocity.

    The calculations do some magic with 1.5 that isn't legal!
    I'm sure the first one must be correct no?

    the second one I I forgot to add the minus haha
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    (Original post by zezno)
    I do think yours is correct as I forgot to include the extra minus sign, so well done!


    btw how did you get 50/1.5 as 49.5? lol

    I think it should be 50/1.5 - 16 = 17.3m/s
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    (Original post by zezno)
    loool omg I'm so confused.
    Me too ugh. But I think I'm right- the question specifically said that direction is changed, so there gotta be a double minus there... I think
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    (Original post by zezno)
    I'm sure the first one must be correct no?

    the second one I I forgot to add the minus haha
    The two solutions to the second question look wrong. The first question looks fine.
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    (Original post by sabruh)
    Name:  image.jpg
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    The step from 50 = .. to 48.5 = .. looks suspect.
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    (Original post by RogerOxon)
    The two solutions to the second question look wrong. The first question looks fine.
    Thanks. I believe it should be:

    50 = 1.5(v--16)
    50 = 1.5(v+16)
    v = 50/1.5 - 16 = 17.3m/s

    thanks again ( I hope that's right loool)
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    (Original post by zezno)
    btw how did you get 50/1.5 as 49.5? lol

    I think it should be 50/1.5 - 16 = 17.3m/s
    I can't use a calculator lmao, looks like I pressed minus instead of divide. DAS the right answer
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    (Original post by RogerOxon)
    The step from 50 = .. to 48.5 = .. looks suspect.
    Yeah, I pressed the wrong button on my calculator. Thanks for spotting it!!
 
 
 
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