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A man is throwing a plate in the air. The plate reaches the height of 40m and the length of 70m. What was the speed of the plate?

This is what I've done

[tex]v_y:[/tex]

[tex]mgh = \frac{mv^2}{2} => v = \sqrt{2gh} = \sqrt{2*9,82*40} = 28m/s[/tex]

[tex]v_x:[/tex]

[tex]v = v_0 + at => t = 28/9,82 = 2,85s[/tex]

[tex]s = vt => v = s/t = 70/2,85 = 24,56m/s[/tex]

[tex]v_z = \sqrt{v_y^2+v_x^2} = \sqrt{24,6^2 + 28^2} = 37m/s[/tex]Code (Text):/|

/ |

/ | v_y = 28m/s

v_z / |

/ |

/ |

/ |

/______________|

v_x = 24,6m/s

But the answer should be 31m/s. What am I doing wrong?

Thank you.

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# Homework Help: Mechanics (speed)

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