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    Hey, I was revising some M1 questions and the following question came up:
    ‘A stone is thrown vertically upwards with speed of 16ms^-1 from point h metres above the ground. The stone hits the ground 4 seconds later. Find:
    The value of h.

    The maths itself seems relatively easy considering it’s only SUVAT, but it’s the mentality obstacle that’s getting to me. The markscheme said the answer is 14.4m and that they used time as 4s. My question is: why’s isn’t time 2 seconds because 4s is the time taken for it to fall to the ground so surely it includes both the time it spends travelling up and then falling back down?
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    Because the object's initial velocity is positive - going upwards for a short period of time while decelerating at 9.81 m/s. You're finding h, which is is the displacement from the point it is launched, if that makes sense.
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    (Original post by Alpacacina)
    Hey, I was revising some M1 questions and the following question came up:
    ‘A stone is thrown vertically upwards with speed of 16ms^-1 from point h metres above the ground. The stone hits the ground 4 seconds later. Find:
    The value of h.

    The maths itself seems relatively easy considering it’s only SUVAT, but it’s the mentality obstacle that’s getting to me. The markscheme said the answer is 14.4m and that they used time as 4s. My question is: why’s isn’t time 2 seconds because 4s is the time taken for it to fall to the ground so surely it includes both the time it spends travelling up and then falling back down?
    I think what your saying is that it would take 2 seconds to go up and 2 seconds to return back down?, but the stone is initiatlly h above the ground, it takes t1 seconds to get to its highest point then another t1 seconds back down to h metres above the ground ( the point It was thrown ) but then it takes t2 seconds to go from that point to the ground beneath it
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    (Original post by uchihaitachi0023)
    I think what your saying is that it would take 2 seconds to go up and 2 seconds to return back down?, but the stone is initiatlly h above the ground, it takes t1 seconds to get to its highest point then another t1 seconds back down to h metres above the ground ( the point It was thrown ) but then it takes t2 seconds to go from that point to the ground beneath it
    Yeah thanks, I misread the question and kind of got stuck to it. It all makes sense now. Thanks
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    The overall displacement is -h, as the ground is h metres below the point of projection
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    (Original post by Alpacacina)
    Hey, I was revising some M1 questions and the following question came up:
    ‘A stone is thrown vertically upwards with speed of 16ms^-1 from point h metres above the ground. The stone hits the ground 4 seconds later. Find:
    The value of h.

    The maths itself seems relatively easy considering it’s only SUVAT, but it’s the mentality obstacle that’s getting to me. The markscheme said the answer is 14.4m and that they used time as 4s. My question is: why’s isn’t time 2 seconds because 4s is the time taken for it to fall to the ground so surely it includes both the time it spends travelling up and then falling back down?
    The question isn't symmetrical, so it wouldn't be 2 seconds each way. The object's initial velocity is upwards, but the acceleration and final displacement is downwards. So be very careful with signs - if you mess them up you may create an equation that doesn't have a solution!
 
 
 
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