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Maths M1 kinematics help Watch

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    Can somebody help me with these two questions please:

    1) A particle is moving with a constant velocity of 15m/s when it is subject to a deceleration of 5m/s^2. Find the time taken to come to rest.

    2) A particle moving in a straight line is subject to a constant retardation of 3m/s^2. If it starts with a constant velocity of 10 m/s, find how long it will take to return to its starting point.

    I think you use the equation v = u + at but i'd need to know v for that, and i don't know how to work that out.

    Thankyou
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    (Original post by iamayesha)
    Can somebody help me with these two questions please:

    1) A particle is moving with a constant velocity of 15m/s when it is subject to a deceleration of 5m/s^2. Find the time taken to come to rest.

    2) A particle moving in a straight line is subject to a constant retardation of 3m/s^2. If it starts with a constant velocity of 10 m/s, find how long it will take to return to its starting point.

    I think you use the equation v = u + at but i'd need to know v for that, and i don't know how to work that out.

    Thankyou
     u=15

v=0

a=-5



v = u + at


    deceleration is 5 so accelaration is -5
    u is 15 as from when it begins decelerating it starts from 15 as thats the speed it was moving at before
    v is 0 because at the end when it comes to rest the velocity will be 0


    Do you know what to do now?
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    (Original post by AdeptDz)
     u=15

v=0

a=-5



v = u + at


    deceleration is 5 so accelaration is -5
    u is 15 as from when it begins decelerating it starts from 15 as thats the speed it was moving at before
    v is 0 because at the end when it comes to rest the velocity will be 0


    Do you know what to do now?
    that makes so much sense how did i not see that! thankyou and yes i do
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    (Original post by iamayesha)
    that makes so much sense how did i not see that! thankyou and yes i do
    You're welcome
 
 
 
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