Question

Автомобиль начал торможение при скорости 72км/ч. определите модуль ускорения автомобиля и время торможения , если тормозной путь автомобиля равен 100 м.

Answer 1

S=(V2-Vo2)/2а
2as=V2-Vo2
a=(V2-Vo2)/2s
a=(0-20)/(2*100)=-0,1м/с2

а=(V-Vo)/t
at=V-Vo
t=(V-Vo)/a
t=(0-20)/(-0,1)=200с

Answer 2

Calculation of Acceleration and Braking Time

To determine the acceleration and braking time of a car, we need to use the given information: the initial speed of the car (72 km/h), and the braking distance (100 m).

First, let's convert the initial speed from km/h to m/s: - 72 km/h = 20 m/s

Next, we can use the following kinematic equation to calculate the acceleration: - v^2 = u^2 + 2as

Where: - v is the final velocity (0 m/s, as the car comes to a stop) - u is the initial velocity (20 m/s) - a is the acceleration - s is the distance traveled during braking (100 m)

Rearranging the equation, we have: - a = (v^2 - u^2) / (2s)

Substituting the values, we get: - a = (0^2 - 20^2) / (2 * 100)

Simplifying the equation, we find: - a = -400 / 200 - a = -2 m/s^2

The negative sign indicates that the car is decelerating.

Now, let's calculate the time it takes for the car to come to a stop. We can use the following equation: - v = u + at

Where: - v is the final velocity (0 m/s) - u is the initial velocity (20 m/s) - a is the acceleration (-2 m/s^2) - t is the time taken to stop (unknown)

Rearranging the equation, we have: - t = (v - u) / a

Substituting the values, we get: - t = (0 - 20) / -2

Simplifying the equation, we find: - t = 20 / 2 - t = 10 seconds

Therefore, the module of acceleration of the car is 2 m/s^2 (negative, indicating deceleration), and the braking time is 10 seconds.

Please note that these calculations assume constant acceleration and do not take into account factors such as air resistance or variations in braking efficiency.