# A bullet flying at a speed of 400 m / s hits an earthen rampart to a depth of 32

A bullet flying at a speed of 400 m / s hits an earthen rampart to a depth of 32 cm for how long did the bullet move inside the rampart? With what acceleration? What was its speed at a depth of 16 cm?

Initial data: V0 (speed before hitting the earth wall) = 400 m / s; h (distance traveled by the bullet in the earthen shaft) = 32 cm = 0.32 m; h1 (considered depth) = 16 cm = 0.16 m.

1) Acceleration inside the shaft: a = (V0 ^ 2 – V ^ 2) / 2h = (400 ^ 2 – 0 ^ 2) / (2 * 0.32) = 250,000 m / s2 (250 km / s2).

2) Time of movement inside the earth shaft: t = (V0 – V) / a = (400 – 0) / 250000 = 0.0016 s = 1.6 ms.

3) Speed at a depth of 16 cm: h1 = (V0 ^ 2 – V ^ 2) / 2a and V = √ (V0 ^ 2 – 2a * h1) = √ (400 ^ 2 – 2 * 250000 * 0.16) = 282.8 m / s.

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