The car moved at a speed of 4 m / s, then turned off the engine and began to brake with an acceleration

The car moved at a speed of 4 m / s, then turned off the engine and began to brake with an acceleration of 1 m / s ^ 2. It will pass within 5 s from the moment of braking.

Task data: V1 (speed with which the given vehicle was moving) = 4 m / s; a (acceleration after turning off the engine) = 1 m / s2; t (duration of braking of a given vehicle) = 5 s.

1 way) The time of movement of a given vehicle to a complete stop: 0 = V1 – a * tх, whence tх = V1 / a = 4/1 = 4 s.

Distance for 5 seconds of braking: S = V1 * tx – a * tx ^ 2/2 = 4 * 4 – 1 * 4 ^ 2/2 = 16 – 8 = 8 m.

Method 2) Distance in 5 seconds of braking: S = (V1 ^ 2 – V2 ^ 2) / 2a = 4 ^ 2 / (2 * 1) = 16/2 = 8 m.