The driver of a locomotive moving at a speed of 70 km / h began to brake at a distance of 1000 m from the station.
| July 1, 2021 | education
The driver of a locomotive moving at a speed of 70 km / h began to brake at a distance of 1000 m from the station. Determine the position of the locomotive after 30 s, if, when braking, its acceleration is 0.2 m / s ^ 2.
V0 = 70 km / h = 19.4 m / s.
S0 = 1000 m.
t1 = 30 s.
a = 0.2 m / s2.
S1 “-?
The path traveled by the locomotive during braking S1 is expressed by the formula: S1 = V0 * t1 – a * t1 ^ 2/2, where V0 is the speed of the locomotive before braking, t is the braking time, and is the acceleration during braking.
S1 = 19.4 m / s * 30 s – 0.2 m / s2 * (30 s) ^ 2/2 = 492 m.
S1 “= S – S1.
S1 “= 1000 m – 492 m = 508 m.
Answer: the locomotive will be at a distance of S1 “= 508 m from the station.
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