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A brick is thrown upward from the top of a building at an angle of 25° to the horizontal and with an initial speed of 15m/s. If the brick is in the flightfor 3.0 s, how tall is the building?

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  1. https://www.jiskha.com/questions/682094/A-brick-is-thrown-upward-from-the-top-of-a-building-at-an-angle-of-25-to-the-horizontal

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  2. Vo = 15m/s[25o],
    Yo = 15*sin25 = 6.3 m/s. = Ver. component of initial velocity.

    Y = Yo + g*Tr = 0,
    6.3 + (-9.8)Tr = 0,
    Tr = 0.65 s. = Rise time.

    Tr + Tf = 3 s,
    0.65 + Tf = 3,
    Tf = 2.35 s. = Fall time.

    ho = 0.5g*Tf^2 = 4.9 * 2.35^2 = 27.1 m. above gnd.

    Y^2 = Yo^2 + 2g*h = 0,
    6.3^2 + (-19.6)h = 0,
    h = 2.03 m. above the bldg.

    hb + h = ho,
    hb + 2.03 = 27.1,
    hb = 25.1 m. = Ht. of the bldg.

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