Question

На скорости V0 = 108 км в час, автомобиль начинает тормозить с ускорением a = 0.4 метра за секунду. Через какое время его скорость уменьшиться в 3 раза? Подробное решение​

Answer 1

V0=108 км/ч=30 м/с

а=-0,4 м/с² (ускорение с минусом, т.к. он тормозит

V=V0/3

t-?

Решение:

V=V0+at => t=(V-V0)/a=(V0/3-V0)/a=(30/3-30)/-0,4= 8 с

Ответ: 8с

Answer 2

Problem Analysis

We are given the initial velocity of a car, V0 = 108 km/h, and the deceleration or negative acceleration, a = 0.4 m/s^2. We need to find the time it takes for the car's velocity to decrease by a factor of 3.

Solution

To solve this problem, we can use the equations of motion. The equation that relates initial velocity (V0), final velocity (V), acceleration (a), and time (t) is:

V = V0 + at

We are given V0 = 108 km/h and a = -0.4 m/s^2. We need to find the time (t) when the velocity (V) is 1/3 of the initial velocity (V0).

Let's substitute the given values into the equation and solve for t:

V = V0 + at

1/3 * V0 = V0 + (-0.4) * t

1/3 * 108 km/h = 108 km/h + (-0.4) * t

36 km/h = 108 km/h - 0.4t

0.4t = 108 km/h - 36 km/h

0.4t = 72 km/h

Converting km/h to m/s:

0.4t = 72 km/h * (1000 m/1 km) * (1 h/3600 s)

0.4t = 20 m/s

Now, we can solve for t:

t = (20 m/s) / 0.4

t = 50 s

Answer

The car's velocity will decrease by a factor of 3 after 50 seconds of braking with an acceleration of 0.4 m/s^2.