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AS Mechanics Please Help :( watch

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    A golf ball is hit from ground level so that its initial velocity is (20i +30j) ms-1 and its acceleration is -10j ms-2, where i and j are horizontal and vertical unit vectors, respectively. Assume that the initial position of the ball is 0i + 0j.

    a) Find the time that the ball is in the air, the position of the point where it hits the ground and its speed at this time.

    b) Find the time for which the height of the ball is greater than 25m.




    Please help xxxx
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    (Original post by buttered)
    A golf ball is hit from ground level so that its initial velocity is (20i +30j) ms-1 and its acceleration is -10j ms-2, where i and j are horizontal and vertical unit vectors, respectively. Assume that the initial position of the ball is 0i + 0j.

    a) Find the time that the ball is in the air, the position of the point where it hits the ground and its speed at this time.

    b) Find the time for which the height of the ball is greater than 25m.




    Please help xxxx
    What do you know about the point where the ball hits the ground (and have you drawn a diagram)?
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    Working vertically first of all: when the ball hits the ground again displacement, s=0. Use your vertical component of the initial speed, j, and use the formula s=ut+0.5at^2, you should be able to set up a quadratic equation and solve for the time of flight.


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    (Original post by tiny hobbit)
    What do you know about the point where the ball hits the ground (and have you drawn a diagram)?
    I have no idea how to start
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    (Original post by buttered)
    I have no idea how to start
    Can you at least write down some SUVAT equations in the i- and j- directions?
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    Can you possibly get a pic of the question it would be much easier to help that way
 
 
 
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