An icicle torn off from the roof falls from the balcony of the 4th floor from a height of 13 m.

An icicle torn off from the roof falls from the balcony of the 4th floor from a height of 13 m. What speed will it have at a height of 2 m?

Eк1 + Eп1 = Eк2 + Eп2, where Eк1 and Eп1 – energy at the beginning of the fall; Eк2 and Ep2 are the energy of the icicle at a height of 2 m.

At the beginning of the fall, V = 0 m, so Eк1 = 0.

En1 = Ek2 + En2.

Ep1 = m * g * h1, m is the mass of the icicle, g is the acceleration of gravity (g = 10 m / s²), h1 is the height (h1 = 13 m).

Eк2 = m * V² / 2, V is the speed of the icicle.

Ep2 = m * g * h2, h2 = 2 m.

m * g * h1 = m * V² / 2 + m * g * h2.

g * h1 = 0.5V² + g * h2.

V = √ ((g * h1 – g * h2) / 0.5) = √ ((10 * 13 – 10 * 2) / 0.5) = 14.83 m / s.