A ball is thrown horizontally from the top of a 20-m high hill. It strikes the ground at an angle of 45 degrees. With what speed was it thro

Question

A ball is thrown horizontally from the top of a 20-m high hill. It strikes the ground at an angle of 45 degrees. With what speed was it thrown?

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Trung Dũng 1 year 2021-09-03T04:12:44+00:00 1 Answers 121 views 0

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    2021-09-03T04:13:58+00:00

    Answer:

    Explanation:

    This is the case of horizontal projection from a height:

    Time, t = sqrt ( 2h / g )

    = sqrt ( 2 * 20 / 9.8 )

    = 2.02 s

    Vfx = V

    Vfy = g* t = 2.02 g

    theta (θ)= 45 deg

    tan theta (tan θ) = Vfy / Vfx

    tan 45 = 2.02 g / V

    V = 2.02 * 9.8

    = 19.8 m/s

    ≅ 20m/s

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