A car traveling 57.7 km/h is 22.2 m from a barrier when the driver slams on the brakes. The car hits the barrier 2.14 s later. (a) What was the car's constant acceleration just before impact? (Assume the car is initially travelling in the positive direction; if the car decelerates in that direction, its acceleration will be a negative number.)

Respuesta :

Explanation:

It is given that,

Initial speed of the car, u = 57.7 km/hr = 16.02 m/s

Distance between the car and the barrier, d = 22.2 m

The car hits the barrier 2.14 s later.

Final speed of the car, v = 0 (at rest)

Let a is the acceleration of the car. It can be calculated using the second equation of motion as :

[tex]d=ut+\dfrac{1}{2}at^2[/tex]

[tex]a=\dfrac{2(d-ut)}{t^2}[/tex]

[tex]a=\dfrac{2(22.2-16.02\times 2.14)}{(2.14)^2}[/tex]

[tex]a=-5.27\ m/s^2[/tex]

As the car decelerates, the acceleration of the car just before the impact is [tex]-5.27\ m/s^2[/tex]. Hence, this is the required solution.