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Thread: Trucks speed...

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    Trucks speed...

    A truck is accelerating over a certain distance (in metres). Its final speed (v m/s) is related to its starting speed (u m/s), according to the rule v=u+1500. Find the truck's starting and final speeds, given that the truck's final speed is 5 times its starting speed.
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  2. #2
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    Quote Originally Posted by lily123 View Post
    A truck is accelerating over a certain distance (in metres). Its final speed (v m/s) is related to its starting speed (u m/s), according to the rule v=u+1500. Find the truck's starting and final speeds, given that the truck's final speed is 5 times its starting speed.
    Let u denote the starting speed. Then you know that $\displaystyle v = 5u$

    Plug in this term into the given equation:

    $\displaystyle (5u)^2=u^2+1500$

    Solve for u. (The negative solution isn't very plausible here)

    Afterwards calculate v.

    I've got $\displaystyle v\approx 39.53\ \frac ms$. That means the final speed of the truck is $\displaystyle 142.3\ \frac{km}h$. In Germany the truck driver would be arrested by the police immediately
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