# A bullet flying at a speed of 400 m / s broke through a wall 20 cm thick, as a result of which the speed

A bullet flying at a speed of 400 m / s broke through a wall 20 cm thick, as a result of which the speed of the bullet decreased to 100 m / s. how long did the bullet move in the wall?

Task data: V0 (initial bullet velocity) = 400 m / s; h (thickness of the punched board) = 20 cm (in SI h = 0.2 m); V (final speed) = 100 m / s.

To determine the duration of the movement of a given bullet in the wall, we apply the formula: h = S = (V + V0) * t / 2, whence t = 2S / (V + V0).

Calculation: t = 2 * 0.2 / (100 + 400) = 0.0008 s or 0.8 ms.

Answer: The target bullet moved in the wall for 0.8 ms.

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