With what minimum acceleration should the car move for an emergency stop before the intersection if its speed

With what minimum acceleration should the car move for an emergency stop before the intersection if its speed at the beginning of braking is 72 km / h. and the distance from the crossroads is 50m.

To determine the minimum acceleration of a given car during an emergency stop, we will use the formula: S = (V ^ 2 – V0 ^ 2) / 2a, whence we express: a = (V ^ 2 V0 ^ 2) / 2S.

Variable values: V – final speed (V = 0 m / s); V0 – speed at the beginning of braking (V0 = 72 km / h = 20 m / s); S – distance to the intersection (S = 50 m).

Let’s perform the calculation: a = (V ^ 2 – V0 ^ 2) / 2S = (0 ^ 2 – 20 ^ 2) / (2 * 50) = -4 m / s2.

Answer: The given car must move in front of the intersection with an acceleration of at least 4 m / s2.