An arrow fired from a bow rose to a height of 30 m. What was the speed of the arrow at a height of 10 m?

The height to which the boom rose:

S = (V² – V0²) / 2a, S – boom lifting height (S = 30 m), V – final speed (V = 0 m / s), V0 – initial speed, а – acceleration (а = -g, g – acceleration of gravity (g = 10 m / s²)).

S = – V0² / 2 * (-g).

V0 = √ (2 * g * S) = √ (2 * 10 * 30) = √ (600) = 24.5 m / s.

Boom speed at 10 m:

S = (V² – V0²) / 2 * (-g).

V² – V0² = -2g * S.

V = √ (-2g * S + V0²) = √ (600 – 2 * 10 * 10) = √ (400) = 20 m / s.