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    Hello! I was doing a WJEC Additional Science P2 Paper and this answer is tripping me up...
    The question states

    'One of the world's tallest roller coasters has an initial peak of height 140m. After reaching the top, the car first falls to a height 50m above the ground before it continues on its journey
    -the mass of the car and passengers is 1200kg, use equations from page 2 to calculate the theoretical maximum velocity of the car after this first fall (g=10m/s²)"

    Now, I did
    PE = mgh
    = 1200 x 10 x (140-50) = 1080000J

    then PE=KE, so KE = 1/2mv²
    1080000 = 1/2 x 1200 x v²
    I rearranged and got 21.21 etc
    But the mark scheme says the velocity is double, 42.4 m/s

    help me out, please???
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    (Original post by CresentHan)
    Hello! I was doing a WJEC Additional Science P2 Paper and this answer is tripping me up...
    The question states

    'One of the world's tallest roller coasters has an initial peak of height 140m. After reaching the top, the car first falls to a height 50m above the ground before it continues on its journey
    -the mass of the car and passengers is 1200kg, use equations from page 2 to calculate the theoretical maximum velocity of the car after this first fall (g=10m/s²)"

    Now, I did
    PE = mgh
    = 1200 x 10 x (140-50) = 1080000J

    then PE=KE, so KE = 1/2mv²
    1080000 = 1/2 x 1200 x v²
    I rearranged and got 21.21 etc
    But the mark scheme says the velocity is double, 42.4 m/s

    help me out, please???
    Yeah I got 42.43 as well - probably you're not rearranging properly

    1080000 = 1/2 x 1200 x v2
    2160000 = 1200 x v2
    1800 = v2
    v = sqrt (1800) = 42.43
 
 
 
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