The boy pushed the sled off the top of the hill. Immediately after the push, the sledges had

The boy pushed the sled off the top of the hill. Immediately after the push, the sledges had a speed of 5m / s, and at the foot of the hill it was 15m / s. The friction of the sled against the snow is negligible. What is the height of the slide?

V0 = 5 m / s.

V = 15 m / s.

g = 10 m / s2.

h -?

At the initial moment of time, the sledges had potential En0 and kinetic energy Ek0. According to the law of conservation of total mechanical energy, during the movement of the sled, the potential energy of the sled En0 passed into kinetic.

En0 + Ek0 = Ek.

We express the potential and kinetic energy by the formulas: Ek0 = m * V0 ^ 2/2, Ek = m * V ^ 2/2, En0 = m * g * h.

m * V0 ^ 2/2 + m * g * h = m * V ^ 2/2.

h = (V ^ 2 – V0 ^ 2) / 2 * g.

h = ((15 m / s) ^ 2 – (5 m / s) ^ 2) / 2 * 10 m / s2 = 10 m.

Answer: the sled has moved down the hill with a height of h = 10 m.