physics

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A boy reaches out of a window and tosses a ball straight up with a speed of 10 m/s. The ball is 20 m above the ground as he releases it. Use energy to find The ball's speed as it passes the window on its way down and speed of impact on the ground.

  • physics -

    Kinetic energy on the way up = kinetic energy on the way down, ignoring air-resistance.

    Therefore speed going up = speed going down = 10 m/s.

    Energy at window level = (1/2)mv0²+mgH
    Energy at ground level = (1/2)mv²
    Equate energies and solve for v.

  • physics -

    Calculated it comes out to be 22

    Kinematics can also be used

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