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    I do not get this question at all. I ahd several attempts but none of them worked. Please help!! Here's the question:

    A test is carried out on a rocket, of mass 200kg, which is fired horizontally at a speed of 50ms-1. The rocket experiences a constant air resistance force of 1568N. It travels a distance of 108m before it hits a stationary tank, of mass 4800kg. Assume that the rocket always travels horizontally.
    (a) Find the speed of the rocket when it has travelled a distance of 108m.
    when the rocket hits the tank it becomes lodged in it.
    (b) Find the speed of the tank and the rocket just after the collision.
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    f=ma
    -1568=200*a
    get a then use suvat
    part b
    momentum before=mom after

    (Original post by Sid.)
    I do not get this question at all. I ahd several attempts but none of them worked. Please help!! Here's the question:

    A test is carried out on a rocket, of mass 200kg, which is fired horizontally at a speed of 50ms-1. The rocket experiences a constant air resistance force of 1568N. It travels a distance of 108m before it hits a stationary tank, of mass 4800kg. Assume that the rocket always travels horizontally.
    (a) Find the speed of the rocket when it has travelled a distance of 108m.
    when the rocket hits the tank it becomes lodged in it.
    (b) Find the speed of the tank and the rocket just after the collision.
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    (Original post by angrypoliceman)
    f=ma
    -1568=200*a
    get a then use suvat
    part b
    momentum before=mom after
    I did use "F=ma" and found a=7.84 and then I used v^2=u^2 + 2as where
    s=108
    u=50
    v=0
    a=7.84
    but it turns out to be incorrect.
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    (Original post by Sid.)
    I did use "F=ma" and found a=7.84 and then I used v^2=u^2 + 2as where
    s=108
    u=50
    v=0
    a=7.84
    but it turns out to be incorrect.
    a should be negative
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    (Original post by angrypoliceman)
    a should be negative
    Sorry, I dont get why it would be negative
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    (Original post by Sid.)
    Sorry, I dont get why it would be negative
    It's slowing down ...
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    (Original post by Sid.)
    Sorry, I dont get why it would be negative
    its decelerating man
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    (Original post by angrypoliceman)
    f=ma
    -1568=200*a
    get a then use suvat
    part b
    momentum before=mom after
    why are you saying the unbalanced force is -1568, it says the resistance force it 1568N. For there to be acceleration there needs to be a thrust force greater than that, but that hasn't been given in the equation.
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    I'm really sorry but I still don't get how would it slow down cause it travels a distance of 108m before it hits a stationary tank, of mass 4800kg. please explain to me!
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    (Original post by NGEO)
    why are you saying the unbalanced force is -1568, it says the resistance force it 1568N. For there to be acceleration there needs to be a thrust force greater than that, but that hasn't been given in the equation.
    You have just confused me now!
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    (Original post by NGEO)
    why are you saying the unbalanced force is -1568, it says the resistance force it 1568N. For there to be acceleration there needs to be a thrust force greater than that, but that hasn't been given in the equation.
    im saying the resultant force is -1568 since theres no forward force on the rocket and a drag force
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    (Original post by Sid.)
    Sorry, I dont get why it would be negative
    Because the rocket is decelerating , the force in the f=ma equation should be negative as the resultant force is negative (F=0-1568)
    (you should get one direction as positive and one direction as negative when first starting the problem)

    so for f=ma is -1568=200a
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    (Original post by Sid.)
    You have just confused me now!
    listen to the guy who got an E in mechanics dude. I know my ****
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    (Original post by angrypoliceman)
    im saying the resultant force is -1568 since theres no forward force on the rocket and a drag force
    Ahhh sorry, i forgot that rocket can slow down. silly me
 
 
 
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