A free falling body reaches the Earth’s surface at a speed of 40 m / s. From what height did it fall?

Task data: free fall (V0 (speed at the beginning of the fall) = 0 m / s); V (final speed, speed at the Earth’s surface) = 40 m / s.

Constants: g (acceleration due to gravity) ≈ 10 m / s2.

1 way) The law of conservation of energy: m * V ^ 2/2 = m * g * h and h = V ^ 2 / (2 * g) = 40 ^ 2 / (2 * 10) = 1600/20 = 80 m.

Method 2) Displacement formula: S = h = (V ^ 2 – V0 ^ 2) / 2a = V ^ 2 / 2g = 80 m.

Answer: The fall started from a height of 80 m.