Question

Problema # 2:

Un auto tiene una velocidad inicial de 45 m/s, el auto frena con una aceleración de 3 m/s², considerando esta información determine:

a. Calcule la velocidad final del auto cuando pasan 2 segundos luego de frenar

b. Calcule cuanto tiempo tardara para detenerse por completo.

c. Calcule la distancia recorrida desde que el auto aplica los frenos hasta que se detiene por completo.

Answer 1

A car has an initial speed of 45 m / s, the car brakes with an acceleration of 3 m / s2, considering this information determine: to. Calculate the final speed of the car when 2 seconds pass after stopping b. Calculate how long it will take to stop completely. c. Calculate the distance traveled since the car applies the brakes until it stops completely.

(a) u = 45 m/s;

acceleration, a = - 3 m/s² (ie retardation);

final speed of the car when t = 2 seconds:

Use equation of kinematics;

v = u + at;

= 45 - 3x2;

= 39 m/s.

(b) Time taken to stop completely:

v = u + at;

0 = 45 - 3xt;   (as final velocity will be zero)

t = 15 sec.

(c) Distance (d) it will covered to stop completely:

v² = u² + 2ad;

0 = 45² - 2x3xd; (as final velocity will be zero)

d = 337.5 m.