During emergency braking, a car moving at a speed of 20 m / s stopped after 5 s. Find the braking time.
| March 6, 2021 | education
V0 = 20 m / s.
V = 0 m / s.
t = 5 s.
S -?
With uniformly accelerated deceleration, the path S traversed by the body is determined by the formula: S = V0 * t – a * t ^ 2/2, where V0 is the body’s speed at the beginning of deceleration, t is the deceleration time, and is the acceleration during deceleration.
The acceleration of the car a when driving, we find according to the definition: a = (V – V0) / t.
Since the final speed is V = 0 m / s, the formula will take the form: a = – V0 / t.
The “-” sign indicates that the speed and acceleration are directed in opposite directions.
S = V0 * t – V0 * t ^ 2/2 * t = V0 * t – V0 * t / 2 = V0 * t / 2.
S = 20 m / s * 5 s / 2 = 50 m.
Answer: the braking distance was S = 50 m.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.
