How to find the height from which the body fell, if its speed during the fall was 1.5 km / h.

Data: V – speed when falling (V = 1.5 km / h, in SI system V = 0.41 (6) m / s).

Const: g – acceleration due to gravity (approx. G ≈ 9.81 m / s2).

1 method) The law of conservation of energy: mt * g * hx = mt * (V ^ 2 – V0 ^ 2) / 2 = mt * V ^ 2/2, whence we express: hx = mt * V ^ 2 / (2 * mt * g) = V ^ 2 / 2g.

Calculation: hx = V ^ 2 / 2g = 0.41 (6) ^ 2 / (2 * 9.81) ≈ 0.00885 m = 8.85 mm.

Method 2) Distance traveled: S = hx = (V ^ 2 – V0 ^ 2) / 2a = (V ^ 2 – 0 ^ 2) / 2g = V ^ 2 / 2g = 8.85 mm.

Answer: The body should have fallen from a height of 8.85 mm.