The bus, traveling at a speed of 54 km / h, began to brake 200 m before the stop.

The bus, traveling at a speed of 54 km / h, began to brake 200 m before the stop. Find the acceleration while doing this.

Initial data: V (bus speed before braking) = 54 km / h; S (distance from the bus to the stop) = 200 m; V (final speed of the bus, the bus will stop) = 0 m / s.

SI system: V = 54 km / h = 54 / 3.6 m / s = 15 m / s.

The acceleration when braking a bus can be expressed from the formula:

S = (V ^ 2 – V0 ^ 2) / 2a = -V0 ^ 2 / 2a; 2a * S = -V0 ^ 2; a = -V0 ^ 2 / 2S.

Let’s do the calculation:

a = -V0 ^ 2 / 2S = -15 ^ 2 / (2 * 200) = -225 / 400 = -0.5625 m / s ^ 2.

Answer: The bus acceleration module is 0.5625 m / s ^ 2.