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    Hi, I worked out a question in the revision guide of edexcel AS mechanics and I got the answer 50 but in the answers it says that it is 42 not 50. I have no idea how that answer could be worked out. Please help me. This is the question:

    A car is travelling along a straight motorway at a constant speed V m/s. Ten seconds after passing a speed-limit sign, the driver brakes and the car decelerates uniformly for 5 seconds, reducing its speed to 30m/s. Given that the car covers a distance of 600m in the 15 second period, find the value of V.

    Anyone, suggestions please?
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    so if you draw a velocity time graph, the area under the graph should be equal to 600 between 1 and 15 seconds.
    The area under the graph = 10V + 5(V-30)/2 + 150 = 600
    450=10V + 5/2V -75
    525=12.5V
    V=42

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    (Original post by atomicjellyfish)
    so if you draw a velocity time graph, the area under the graph should be equal to 600 between 1 and 15 seconds.
    The area under the graph = 10V + 5(V-30)/2 + 150 = 600
    450=10V + 5/2V -75
    525=12.5V
    V=42

    Name:  hbh.png
Views: 29
Size:  3.9 KB
    Hey extremely thanks.
 
 
 
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