The bus travels at a speed of 54 km / h. At what distance from the stop should the driver start braking

| September 20, 2021 | education

The bus travels at a speed of 54 km / h. At what distance from the stop should the driver start braking if, for the convenience of passengers, the acceleration should not exceed 1.2 m / s2

It is known from the problem statement that the bus moves at a speed of v₀ = 54 km / h = 15 m / s. Moreover, for the convenience of passengers, acceleration should not exceed the value: | a | = 1.2 m / s ^ 2. To determine at what distance S from the stop the driver should start braking, we will use the formula for calculating the distance for a straight-line uniformly accelerated movement:

S = (v ^ 2 – v₀ ^ 2) / (2 ∙ a).

Since when braking v = 0 m / s, and the acceleration is negative: a = – 1.2 m / s ^ 2, we get:

S = (0 ^ 2 – (15 m / s) ^ 2) / (2 ∙ (- 1.2 m / s ^ 2)) = 93.75 m.

But since | a | ≤ 1.2 m / s ^ 2, then S ≥ 93.75 m.

Answer: the driver must start braking at a distance of at least 93.75 meters from the stop.



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